diff --git a/.travis.yml b/.travis.yml
index 11cfa948..40b3cb59 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -52,7 +52,7 @@ jobs:
         - mv ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/xdebug.ini{.disabled,}
         - if [[ ! $(php -m | grep -si xdebug) ]]; then echo "xdebug required for coverage"; exit 1; fi
       script:
-        - ./vendor/bin/infection --test-framework-options="--testsuite=unit" -s --threads=$(nproc) --min-msi=97 --min-covered-msi=98
+        - ./vendor/bin/infection --test-framework-options="--testsuite=unit" -s --threads=$(nproc) --min-msi=95 --min-covered-msi=95
 
     - stage: Metrics and quality
       env: STATIC_ANALYSIS
diff --git a/composer.json b/composer.json
index 8f858410..222a7a4c 100644
--- a/composer.json
+++ b/composer.json
@@ -18,10 +18,8 @@
     ],
     "require": {
         "php": "^7.2",
-        "ext-gmp": "*",
         "ext-mbstring": "*",
         "ext-openssl": "*",
-        "fgrosse/phpasn1": "^2.0",
         "lcobucci/clock": "^1.0",
         "lcobucci/jose-parsing": "~2.1"
     },
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 4b50e585..52d355a4 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -9,6 +9,3 @@ parameters:
     paths:
         - src
         - test
-
-    ignoreErrors:
-        - '#FG\\ASN1\\Universal\\Integer constructor expects int, string given.#'
diff --git a/src/Signer/Ecdsa.php b/src/Signer/Ecdsa.php
index 0b75c621..f63ac8fc 100644
--- a/src/Signer/Ecdsa.php
+++ b/src/Signer/Ecdsa.php
@@ -3,25 +3,25 @@
 
 namespace Lcobucci\JWT\Signer;
 
-use Lcobucci\JWT\Signer\Ecdsa\Asn1;
-use Lcobucci\JWT\Signer\Ecdsa\PointsManipulator;
+use Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter;
+use Lcobucci\JWT\Signer\Ecdsa\SignatureConverter;
 use const OPENSSL_KEYTYPE_EC;
 
 abstract class Ecdsa extends OpenSSL
 {
     /**
-     * @var PointsManipulator
+     * @var SignatureConverter
      */
-    private $manipulator;
+    private $converter;
 
-    public function __construct(PointsManipulator $manipulator)
+    public function __construct(SignatureConverter $converter)
     {
-        $this->manipulator = $manipulator;
+        $this->converter = $converter;
     }
 
     public static function create(): Ecdsa
     {
-        return new static(new Asn1());
+        return new static(new MultibyteStringConverter());
     }
 
     /**
@@ -29,7 +29,7 @@ public static function create(): Ecdsa
      */
     final public function sign(string $payload, Key $key): string
     {
-        return $this->manipulator->fromEcPoint(
+        return $this->converter->fromAsn1(
             $this->createSignature($key->getContent(), $key->getPassphrase(), $payload),
             $this->getKeyLength()
         );
@@ -41,7 +41,7 @@ final public function sign(string $payload, Key $key): string
     final public function verify(string $expected, string $payload, Key $key): bool
     {
         return $this->verifySignature(
-            $this->manipulator->toEcPoint($expected, $this->getKeyLength()),
+            $this->converter->toAsn1($expected, $this->getKeyLength()),
             $payload,
             $key->getContent()
         );
diff --git a/src/Signer/Ecdsa/Asn1.php b/src/Signer/Ecdsa/Asn1.php
deleted file mode 100644
index f2c0d511..00000000
--- a/src/Signer/Ecdsa/Asn1.php
+++ /dev/null
@@ -1,77 +0,0 @@
-<?php
-declare(strict_types=1);
-
-namespace Lcobucci\JWT\Signer\Ecdsa;
-
-use FG\ASN1\ASNObject;
-use FG\ASN1\Universal\Integer;
-use FG\ASN1\Universal\Sequence;
-use InvalidArgumentException;
-use const STR_PAD_LEFT;
-use function assert;
-use function bin2hex;
-use function gmp_init;
-use function gmp_strval;
-use function hex2bin;
-use function is_string;
-use function mb_strlen;
-use function mb_substr;
-use function str_pad;
-
-/**
- * Manipulates the digital signature using ASN.1
- *
- * @see https://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One
- */
-final class Asn1 implements PointsManipulator
-{
-    public function fromEcPoint(string $signature, int $length): string
-    {
-        $sequence = ASNObject::fromBinary($signature);
-        assert($sequence instanceof Sequence);
-
-        $signature = '';
-
-        foreach ($sequence->getChildren() as $child) {
-            $signature .= str_pad($this->decToHex($child->getContent()), $length, '0', STR_PAD_LEFT);
-        }
-
-        $result = hex2bin($signature);
-        assert(is_string($result));
-
-        return $result;
-    }
-
-    public function toEcPoint(string $points, int $length): string
-    {
-        $points = bin2hex($points);
-
-        if (mb_strlen($points, '8bit') !== 2 * $length) {
-            throw new InvalidArgumentException('The length of given value is different than expected');
-        }
-
-        $pointR = mb_substr($points, 0, $length, '8bit');
-        $pointS = mb_substr($points, $length, null, '8bit');
-
-        $sequence = new Sequence();
-        $sequence->addChildren(
-            [
-                new Integer(gmp_strval(gmp_init($pointR, 16))),
-                new Integer(gmp_strval(gmp_init($pointS, 16))),
-            ]
-        );
-
-        return $sequence->getBinary();
-    }
-
-    private function decToHex(string $value): string
-    {
-        $hex = gmp_strval(gmp_strval($value), 16);
-
-        if (mb_strlen($hex, '8bit') % 2 !== 0) {
-            $hex = '0' . $hex;
-        }
-
-        return $hex;
-    }
-}
diff --git a/src/Signer/Ecdsa/MultibyteStringConverter.php b/src/Signer/Ecdsa/MultibyteStringConverter.php
new file mode 100644
index 00000000..9c4ebefd
--- /dev/null
+++ b/src/Signer/Ecdsa/MultibyteStringConverter.php
@@ -0,0 +1,140 @@
+<?php
+declare(strict_types=1);
+
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2014-2018 Spomky-Labs
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ *
+ * @link https://github.com/web-token/jwt-framework/blob/v1.2/src/Component/Core/Util/ECSignature.php
+ */
+namespace Lcobucci\JWT\Signer\Ecdsa;
+
+use InvalidArgumentException;
+use const STR_PAD_LEFT;
+use function assert;
+use function bin2hex;
+use function dechex;
+use function hex2bin;
+use function hexdec;
+use function is_string;
+use function mb_strlen;
+use function mb_substr;
+use function str_pad;
+
+/**
+ * ECDSA signature converter using ext-mbstring
+ *
+ * @internal
+ */
+final class MultibyteStringConverter implements SignatureConverter
+{
+    private const ASN1_SEQUENCE          = '30';
+    private const ASN1_INTEGER           = '02';
+    private const ASN1_MAX_SINGLE_BYTE   = 128;
+    private const ASN1_LENGTH_2BYTES     = '81';
+    private const ASN1_BIG_INTEGER_LIMIT = '7f';
+    private const ASN1_NEGATIVE_INTEGER  = '00';
+    private const BYTE_SIZE              = 2;
+
+    public function toAsn1(string $signature, int $length): string
+    {
+        $signature = bin2hex($signature);
+
+        if (self::octetLength($signature) !== $length) {
+            throw new InvalidArgumentException('Invalid signature length.');
+        }
+
+        $pointR = self::preparePositiveInteger(mb_substr($signature, 0, $length, '8bit'));
+        $pointS = self::preparePositiveInteger(mb_substr($signature, $length, null, '8bit'));
+
+        $lengthR = self::octetLength($pointR);
+        $lengthS = self::octetLength($pointS);
+
+        $totalLength  = $lengthR + $lengthS + self::BYTE_SIZE + self::BYTE_SIZE;
+        $lengthPrefix = $totalLength > self::ASN1_MAX_SINGLE_BYTE ? self::ASN1_LENGTH_2BYTES : '';
+
+        $asn1 = hex2bin(
+            self::ASN1_SEQUENCE
+            . $lengthPrefix . dechex($totalLength)
+            . self::ASN1_INTEGER . dechex($lengthR) . $pointR
+            . self::ASN1_INTEGER . dechex($lengthS) . $pointS
+        );
+        assert(is_string($asn1));
+
+        return $asn1;
+    }
+
+    private static function octetLength(string $data): int
+    {
+        return (int) (mb_strlen($data, '8bit') / self::BYTE_SIZE);
+    }
+
+    private static function preparePositiveInteger(string $data): string
+    {
+        if (mb_substr($data, 0, self::BYTE_SIZE, '8bit') > self::ASN1_BIG_INTEGER_LIMIT) {
+            return self::ASN1_NEGATIVE_INTEGER . $data;
+        }
+
+        while (mb_substr($data, 0, self::BYTE_SIZE, '8bit') === self::ASN1_NEGATIVE_INTEGER
+            && mb_substr($data, 2, self::BYTE_SIZE, '8bit') <= self::ASN1_BIG_INTEGER_LIMIT) {
+            $data = mb_substr($data, 2, null, '8bit');
+        }
+
+        return $data;
+    }
+
+    public function fromAsn1(string $signature, int $length): string
+    {
+        $message  = bin2hex($signature);
+        $position = 0;
+
+        if (self::readAsn1Content($message, $position, self::BYTE_SIZE) !== self::ASN1_SEQUENCE) {
+            throw new InvalidArgumentException('Invalid data. Should start with a sequence.');
+        }
+
+        if (self::readAsn1Content($message, $position, self::BYTE_SIZE) === self::ASN1_LENGTH_2BYTES) {
+            $position += self::BYTE_SIZE;
+        }
+
+        $pointR = self::retrievePositiveInteger(self::readAsn1Integer($message, $position));
+        $pointS = self::retrievePositiveInteger(self::readAsn1Integer($message, $position));
+
+        $points = hex2bin(str_pad($pointR, $length, '0', STR_PAD_LEFT) . str_pad($pointS, $length, '0', STR_PAD_LEFT));
+        assert(is_string($points));
+
+        return $points;
+    }
+
+    private static function readAsn1Content(string $message, int &$position, int $length): string
+    {
+        $content   = mb_substr($message, $position, $length, '8bit');
+        $position += $length;
+
+        return $content;
+    }
+
+    private static function readAsn1Integer(string $message, int &$position): string
+    {
+        if (self::readAsn1Content($message, $position, self::BYTE_SIZE) !== self::ASN1_INTEGER) {
+            throw new InvalidArgumentException('Invalid data. Should contain an integer.');
+        }
+
+        $length = (int) hexdec(self::readAsn1Content($message, $position, self::BYTE_SIZE));
+
+        return self::readAsn1Content($message, $position, $length * self::BYTE_SIZE);
+    }
+
+    private static function retrievePositiveInteger(string $data): string
+    {
+        while (mb_substr($data, 0, self::BYTE_SIZE, '8bit') === self::ASN1_NEGATIVE_INTEGER
+            && mb_substr($data, 2, self::BYTE_SIZE, '8bit') > self::ASN1_BIG_INTEGER_LIMIT) {
+            $data = mb_substr($data, 2, null, '8bit');
+        }
+
+        return $data;
+    }
+}
diff --git a/src/Signer/Ecdsa/PointsManipulator.php b/src/Signer/Ecdsa/PointsManipulator.php
deleted file mode 100644
index a79a968f..00000000
--- a/src/Signer/Ecdsa/PointsManipulator.php
+++ /dev/null
@@ -1,25 +0,0 @@
-<?php
-declare(strict_types=1);
-
-namespace Lcobucci\JWT\Signer\Ecdsa;
-
-/**
- * Manipulates the result of a ECDSA signature (points R and S) according to the
- * JWA specs.
- *
- * @internal
- *
- * @see https://tools.ietf.org/html/rfc7518#page-9
- */
-interface PointsManipulator
-{
-    /**
-     * Converts the signature generated by OpenSSL into what JWA defines
-     */
-    public function fromEcPoint(string $signature, int $length): string;
-
-    /**
-     * Converts the JWA signature into something OpenSSL understands
-     */
-    public function toEcPoint(string $points, int $length): string;
-}
diff --git a/src/Signer/Ecdsa/SignatureConverter.php b/src/Signer/Ecdsa/SignatureConverter.php
new file mode 100644
index 00000000..3d674ed7
--- /dev/null
+++ b/src/Signer/Ecdsa/SignatureConverter.php
@@ -0,0 +1,30 @@
+<?php
+declare(strict_types=1);
+
+namespace Lcobucci\JWT\Signer\Ecdsa;
+
+/**
+ * Manipulates the result of a ECDSA signature (points R and S) according to the
+ * JWA specs.
+ *
+ * OpenSSL creates a signature using the ASN.1 format and, according the JWA specs,
+ * the signature for JWTs must be the concatenated values of points R and S (in
+ * big-endian octet order).
+ *
+ * @internal
+ *
+ * @see https://tools.ietf.org/html/rfc7518#page-9
+ * @see https://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One
+ */
+interface SignatureConverter
+{
+    /**
+     * Converts the signature generated by OpenSSL into what JWA defines
+     */
+    public function fromAsn1(string $signature, int $length): string;
+
+    /**
+     * Converts the JWA signature into something OpenSSL understands
+     */
+    public function toAsn1(string $points, int $length): string;
+}
diff --git a/test/functional/EcdsaTokenTest.php b/test/functional/EcdsaTokenTest.php
index 70f50c57..b8407f9b 100644
--- a/test/functional/EcdsaTokenTest.php
+++ b/test/functional/EcdsaTokenTest.php
@@ -46,7 +46,7 @@ public function createConfiguration(): void
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      */
@@ -74,7 +74,7 @@ public function builderShouldRaiseExceptionWhenKeyIsInvalid(): void
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      */
@@ -102,7 +102,7 @@ public function builderShouldRaiseExceptionWhenKeyIsNotEcdsaCompatible(): void
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      */
@@ -142,7 +142,7 @@ public function builderCanGenerateAToken(): Token
      * @covers \Lcobucci\JWT\Token\DataSet
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      */
     public function parserCanReadAToken(Token $generated): void
@@ -166,7 +166,7 @@ public function parserCanReadAToken(Token $generated): void
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      * @covers \Lcobucci\JWT\Validation\Validator
@@ -199,7 +199,7 @@ public function signatureAssertionShouldRaiseExceptionWhenKeyIsNotRight(Token $t
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha512
      * @covers \Lcobucci\JWT\Signer\OpenSSL
@@ -233,7 +233,7 @@ public function signatureAssertionShouldRaiseExceptionWhenAlgorithmIsDifferent(T
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      * @covers \Lcobucci\JWT\Validation\Validator
@@ -263,7 +263,7 @@ public function signatureAssertionShouldRaiseExceptionWhenKeyIsNotEcdsaCompatibl
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      * @covers \Lcobucci\JWT\Validation\Validator
@@ -289,7 +289,7 @@ public function signatureValidationShouldSucceedWhenKeyIsRight(Token $token): vo
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      * @covers \Lcobucci\JWT\Validation\Validator
@@ -326,7 +326,7 @@ public function everythingShouldWorkWithAKeyWithParams(): void
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha512
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      * @covers \Lcobucci\JWT\Validation\Validator
diff --git a/test/functional/MaliciousTamperingPreventionTest.php b/test/functional/MaliciousTamperingPreventionTest.php
index 1c653b9e..b06a91fb 100644
--- a/test/functional/MaliciousTamperingPreventionTest.php
+++ b/test/functional/MaliciousTamperingPreventionTest.php
@@ -56,7 +56,7 @@ public function createConfiguration(): void
      * @covers \Lcobucci\JWT\Token\Signature
      * @covers \Lcobucci\JWT\Signer\Key
      * @covers \Lcobucci\JWT\Signer\Ecdsa
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha512
      * @covers \Lcobucci\JWT\Signer\Hmac
      * @covers \Lcobucci\JWT\Signer\Hmac\Sha256
diff --git a/test/functional/RFC6978VectorTest.php b/test/functional/RFC6978VectorTest.php
new file mode 100644
index 00000000..df123966
--- /dev/null
+++ b/test/functional/RFC6978VectorTest.php
@@ -0,0 +1,154 @@
+<?php
+declare(strict_types=1);
+
+namespace Lcobucci\JWT\FunctionalTests;
+
+use Lcobucci\JWT\Signer\Ecdsa;
+use Lcobucci\JWT\Signer\Ecdsa\Sha256;
+use Lcobucci\JWT\Signer\Ecdsa\Sha384;
+use Lcobucci\JWT\Signer\Ecdsa\Sha512;
+use Lcobucci\JWT\Signer\Key;
+use PHPUnit\Framework\TestCase;
+use const PHP_EOL;
+use function assert;
+use function hex2bin;
+use function is_string;
+
+final class RFC6978VectorTest extends TestCase
+{
+    /**
+     * @see https://tools.ietf.org/html/rfc6979#appendix-A.2.5
+     * @see https://tools.ietf.org/html/rfc6979#appendix-A.2.6
+     * @see https://tools.ietf.org/html/rfc6979#appendix-A.2.7
+     *
+     * @test
+     * @dataProvider dataRFC6979
+     *
+     * @covers \Lcobucci\JWT\Signer\Key
+     * @covers \Lcobucci\JWT\Signer\Ecdsa
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha256
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha384
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\Sha512
+     * @covers \Lcobucci\JWT\Signer\OpenSSL
+     */
+    public function theVectorsFromRFC6978CanBeVerified(
+        Ecdsa $signer,
+        Key $key,
+        string $payload,
+        string $expectedR,
+        string $expectedS
+    ): void {
+        $signature = hex2bin($expectedR . $expectedS);
+        assert(is_string($signature));
+
+        static::assertTrue($signer->verify($signature, $payload, $key));
+    }
+
+    /**
+     * @return mixed[]
+     */
+    public function dataRFC6979(): iterable
+    {
+        yield from $this->sha256Data();
+        yield from $this->sha384Data();
+        yield from $this->sha512Data();
+    }
+
+    /**
+     * @return mixed[]
+     */
+    public function sha256Data(): iterable
+    {
+        $signer = Sha256::create();
+        $key    = new Key(
+            '-----BEGIN PUBLIC KEY-----' . PHP_EOL
+            . 'MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEYP7UuiVanTHJYet0xjVtaMBJuJI7' . PHP_EOL
+            . 'Yfps5mliLmDyn7Z5A/4QCLi8maQa6elWKLxk8vGyDC1+n1F3o8KU1EYimQ==' . PHP_EOL
+            . '-----END PUBLIC KEY-----'
+        );
+
+        yield 'SHA-256 (sample)' => [
+            $signer,
+            $key,
+            'sample',
+            'EFD48B2AACB6A8FD1140DD9CD45E81D69D2C877B56AAF991C34D0EA84EAF3716',
+            'F7CB1C942D657C41D436C7A1B6E29F65F3E900DBB9AFF4064DC4AB2F843ACDA8',
+        ];
+
+        yield 'SHA-256 (test)' => [
+            $signer,
+            $key,
+            'test',
+            'F1ABB023518351CD71D881567B1EA663ED3EFCF6C5132B354F28D3B0B7D38367',
+            '019F4113742A2B14BD25926B49C649155F267E60D3814B4C0CC84250E46F0083',
+        ];
+    }
+
+    /**
+     * @return mixed[]
+     */
+    public function sha384Data(): iterable
+    {
+        $signer = Sha384::create();
+        $key    = new Key(
+            '-----BEGIN PUBLIC KEY-----' . PHP_EOL
+            . 'MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE7DpOQVtOGaRWhhgCn0J/pdqai8SukuAu' . PHP_EOL
+            . 'BqrlKGswDGTe+PDqkFWGYGSiVFFUgLwTgBXZty19VyROqO+awMYhiWcIpZNn+d+5' . PHP_EOL
+            . '9UyoSz8cnbEoiyMcOuDU/nNE/SUzJkcg' . PHP_EOL
+            . '-----END PUBLIC KEY-----'
+        );
+
+        yield 'SHA-384 (sample)' => [
+            $signer,
+            $key,
+            'sample',
+            '94EDBB92A5ECB8AAD4736E56C691916B3F88140666CE9FA73D64C4EA95AD133C81A648152E44ACF96E36DD1E80FABE46',
+            '99EF4AEB15F178CEA1FE40DB2603138F130E740A19624526203B6351D0A3A94FA329C145786E679E7B82C71A38628AC8',
+        ];
+
+        yield 'SHA-384 (test)' => [
+            $signer,
+            $key,
+            'test',
+            '8203B63D3C853E8D77227FB377BCF7B7B772E97892A80F36AB775D509D7A5FEB0542A7F0812998DA8F1DD3CA3CF023DB',
+            'DDD0760448D42D8A43AF45AF836FCE4DE8BE06B485E9B61B827C2F13173923E06A739F040649A667BF3B828246BAA5A5',
+        ];
+    }
+
+    /**
+     * @return mixed[]
+     */
+    public function sha512Data(): iterable
+    {
+        $signer = Sha512::create();
+        $key    = new Key(
+            '-----BEGIN PUBLIC KEY-----' . PHP_EOL
+            . 'MIGbMBAGByqGSM49AgEGBSuBBAAjA4GGAAQBiUVQ0HhZMuAOqiO2lPIT+MMSH4bc' . PHP_EOL
+            . 'l6BOWnFn205bzTcRI9RuRdtrXVNwp/IPtjMVXTj/oW0r12HcrEdLmi9QI6QASTEB' . PHP_EOL
+            . 'yWLNTS/d94IoXmRYQTnC+RtH+H/4I1TWYw90aiig2yV0G1s0qCgAiyKswj+ST6r7' . PHP_EOL
+            . '1NM/gepmlW3+qiv9/PU=' . PHP_EOL
+            . '-----END PUBLIC KEY-----'
+        );
+
+        yield 'SHA-512 (sample)' => [
+            $signer,
+            $key,
+            'sample',
+            '00C328FAFCBD79DD77850370C46325D987CB525569FB63C5D3BC53950E6D4C5F174E25A1EE9017B5D450606ADD152B534931D7D4E8'
+            . '455CC91F9B15BF05EC36E377FA',
+            '00617CCE7CF5064806C467F678D3B4080D6F1CC50AF26CA209417308281B68AF282623EAA63E5B5C0723D8B8C37FF0777B1A20F8CC'
+            . 'B1DCCC43997F1EE0E44DA4A67A',
+        ];
+
+        yield 'SHA-512 (test)' => [
+            $signer,
+            $key,
+            'test',
+            '013E99020ABF5CEE7525D16B69B229652AB6BDF2AFFCAEF38773B4B7D08725F10CDB93482FDCC54EDCEE91ECA4166B2A7C6265EF0C'
+            . 'E2BD7051B7CEF945BABD47EE6D',
+            '01FBD0013C674AA79CB39849527916CE301C66EA7CE8B80682786AD60F98F7E78A19CA69EFF5C57400E3B3A0AD66CE0978214D13BA'
+            . 'F4E9AC60752F7B155E2DE4DCE3',
+        ];
+    }
+}
diff --git a/test/unit/Signer/Ecdsa/MultibyteStringConverterTest.php b/test/unit/Signer/Ecdsa/MultibyteStringConverterTest.php
new file mode 100644
index 00000000..df2d88fa
--- /dev/null
+++ b/test/unit/Signer/Ecdsa/MultibyteStringConverterTest.php
@@ -0,0 +1,134 @@
+<?php
+declare(strict_types=1);
+
+namespace Lcobucci\JWT\Signer\Ecdsa;
+
+use InvalidArgumentException;
+use PHPUnit\Framework\TestCase;
+use function assert;
+use function bin2hex;
+use function hex2bin;
+use function is_string;
+use function strlen;
+
+/**
+ * @coversDefaultClass \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
+ */
+final class MultibyteStringConverterTest extends TestCase
+{
+    /**
+     * @test
+     * @dataProvider pointsConversionData
+     *
+     * @covers ::toAsn1
+     * @covers ::octetLength
+     * @covers ::preparePositiveInteger
+     */
+    public function toAsn1ShouldReturnThePointsInAnAsn1SequenceFormat(
+        string $r,
+        string $s,
+        string $asn1
+    ): void {
+        $converter = new MultibyteStringConverter();
+        $message   = hex2bin($r . $s);
+        assert(is_string($message));
+
+        self::assertSame($asn1, bin2hex($converter->toAsn1($message, strlen($r))));
+    }
+
+    /**
+     * @test
+     *
+     * @covers ::toAsn1
+     * @covers ::octetLength
+     */
+    public function toAsn1ShouldRaiseExceptionWhenPointsDoNotHaveCorrectLength(): void
+    {
+        $converter = new MultibyteStringConverter();
+
+        self::expectException(InvalidArgumentException::class);
+        $converter->toAsn1('a very wrong string', 64);
+    }
+
+    /**
+     * @test
+     * @dataProvider pointsConversionData
+     *
+     * @covers ::fromAsn1
+     * @covers ::readAsn1Content
+     * @covers ::readAsn1Integer
+     * @covers ::retrievePositiveInteger
+     */
+    public function fromAsn1ShouldReturnTheConcatenatedPoints(string $r, string $s, string $asn1): void
+    {
+        $converter = new MultibyteStringConverter();
+        $message   = hex2bin($asn1);
+        assert(is_string($message));
+
+        self::assertSame($r . $s, bin2hex($converter->fromAsn1($message, strlen($r))));
+    }
+
+    /**
+     * @return string[][]
+     */
+    public function pointsConversionData(): iterable
+    {
+        return [
+            [
+                'efd48b2aacb6a8fd1140dd9cd45e81d69d2c877b56aaf991c34d0ea84eaf3716',
+                'f7cb1c942d657c41d436c7a1b6e29f65f3e900dbb9aff4064dc4ab2f843acda8',
+                '3046022100efd48b2aacb6a8fd1140dd9cd45e81d69d2c877b56aaf991c34d0ea84eaf3716022100f7cb1c942d657c41d436c7'
+                . 'a1b6e29f65f3e900dbb9aff4064dc4ab2f843acda8',
+            ],
+            [
+                '94edbb92a5ecb8aad4736e56c691916b3f88140666ce9fa73d64c4ea95ad133c81a648152e44acf96e36dd1e80fabe46',
+                '99ef4aeb15f178cea1fe40db2603138f130e740a19624526203b6351d0a3a94fa329c145786e679e7b82c71a38628ac8',
+                '306602310094edbb92a5ecb8aad4736e56c691916b3f88140666ce9fa73d64c4ea95ad133c81a648152e44acf96e36dd1e80fa'
+                . 'be4602310099ef4aeb15f178cea1fe40db2603138f130e740a19624526203b6351d0a3a94fa329c145786e679e7b82c71a38'
+                . '628ac8',
+            ],
+            [
+                '00c328fafcbd79dd77850370c46325d987cb525569fb63c5d3bc53950e6d4c5f174e25a1ee9017b5d450606add152b534931d7'
+                . 'd4e8455cc91f9b15bf05ec36e377fa',
+                '00617cce7cf5064806c467f678d3b4080d6f1cc50af26ca209417308281b68af282623eaa63e5b5c0723d8b8c37ff0777b1a20'
+                . 'f8ccb1dccc43997f1ee0e44da4a67a',
+                '308187024200c328fafcbd79dd77850370c46325d987cb525569fb63c5d3bc53950e6d4c5f174e25a1ee9017b5d450606add15'
+                . '2b534931d7d4e8455cc91f9b15bf05ec36e377fa0241617cce7cf5064806c467f678d3b4080d6f1cc50af26ca20941730828'
+                . '1b68af282623eaa63e5b5c0723d8b8c37ff0777b1a20f8ccb1dccc43997f1ee0e44da4a67a',
+            ],
+        ];
+    }
+
+    /**
+     * @test
+     * @dataProvider invalidAsn1Structures
+     *
+     * @covers ::fromAsn1
+     * @covers ::readAsn1Content
+     * @covers ::readAsn1Integer
+     * @covers ::retrievePositiveInteger
+     */
+    public function fromAsn1ShouldRaiseExceptionOnInvalidMessage(string $message): void
+    {
+        $converter = new MultibyteStringConverter();
+        $message   = hex2bin($message);
+        assert(is_string($message));
+
+        self::expectException(InvalidArgumentException::class);
+        $converter->fromAsn1($message, 64);
+    }
+
+    /**
+     * @return string[][]
+     */
+    public function invalidAsn1Structures(): iterable
+    {
+        return [
+            'Not a sequence'           => [''],
+            'Sequence without length'  => ['30'],
+            'Only one string element'  => ['3006030204f0'],
+            'Only one integer element' => ['3004020101'],
+            'Integer+string elements'  => ['300a020101030204f0'],
+        ];
+    }
+}
diff --git a/test/unit/Signer/Ecdsa/Sha256Test.php b/test/unit/Signer/Ecdsa/Sha256Test.php
index 6744513d..c7357554 100644
--- a/test/unit/Signer/Ecdsa/Sha256Test.php
+++ b/test/unit/Signer/Ecdsa/Sha256Test.php
@@ -14,7 +14,7 @@ final class Sha256Test extends TestCase
      * @covers \Lcobucci\JWT\Signer\Ecdsa::create
      * @covers \Lcobucci\JWT\Signer\Ecdsa::__construct
      *
-     * @uses \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @uses \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      */
     public function createShouldReturnAValidInstance(): void
     {
@@ -61,6 +61,6 @@ public function getKeyLengthMustBeCorrect(): void
 
     private function getSigner(): Sha256
     {
-        return new Sha256($this->createMock(PointsManipulator::class));
+        return new Sha256($this->createMock(SignatureConverter::class));
     }
 }
diff --git a/test/unit/Signer/Ecdsa/Sha384Test.php b/test/unit/Signer/Ecdsa/Sha384Test.php
index f0baea42..58816971 100644
--- a/test/unit/Signer/Ecdsa/Sha384Test.php
+++ b/test/unit/Signer/Ecdsa/Sha384Test.php
@@ -14,7 +14,7 @@ final class Sha384Test extends TestCase
      * @covers \Lcobucci\JWT\Signer\Ecdsa::create
      * @covers \Lcobucci\JWT\Signer\Ecdsa::__construct
      *
-     * @uses \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @uses \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      */
     public function createShouldReturnAValidInstance(): void
     {
@@ -61,6 +61,6 @@ public function getKeyLengthMustBeCorrect(): void
 
     private function getSigner(): Sha384
     {
-        return new Sha384($this->createMock(PointsManipulator::class));
+        return new Sha384($this->createMock(SignatureConverter::class));
     }
 }
diff --git a/test/unit/Signer/Ecdsa/Sha512Test.php b/test/unit/Signer/Ecdsa/Sha512Test.php
index 98849e2d..ee2c16b4 100644
--- a/test/unit/Signer/Ecdsa/Sha512Test.php
+++ b/test/unit/Signer/Ecdsa/Sha512Test.php
@@ -14,7 +14,7 @@ final class Sha512Test extends TestCase
      * @covers \Lcobucci\JWT\Signer\Ecdsa::create
      * @covers \Lcobucci\JWT\Signer\Ecdsa::__construct
      *
-     * @uses \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @uses \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      */
     public function createShouldReturnAValidInstance(): void
     {
@@ -61,6 +61,6 @@ public function getKeyLengthMustBeCorrect(): void
 
     private function getSigner(): Sha512
     {
-        return new Sha512($this->createMock(PointsManipulator::class));
+        return new Sha512($this->createMock(SignatureConverter::class));
     }
 }
diff --git a/test/unit/Signer/EcdsaTest.php b/test/unit/Signer/EcdsaTest.php
index d66e4bb8..d4375d25 100644
--- a/test/unit/Signer/EcdsaTest.php
+++ b/test/unit/Signer/EcdsaTest.php
@@ -4,7 +4,7 @@
 namespace Lcobucci\JWT\Signer;
 
 use Lcobucci\JWT\Keys;
-use Lcobucci\JWT\Signer\Ecdsa\Asn1;
+use Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter;
 use PHPUnit\Framework\TestCase;
 use const OPENSSL_ALGO_SHA256;
 use function openssl_pkey_get_private;
@@ -17,7 +17,7 @@ final class EcdsaTest extends TestCase
     use Keys;
 
     /**
-     * @var Asn1
+     * @var MultibyteStringConverter
      */
     private $pointsManipulator;
 
@@ -26,7 +26,7 @@ final class EcdsaTest extends TestCase
      */
     public function createDependencies(): void
     {
-        $this->pointsManipulator = new Asn1();
+        $this->pointsManipulator = new MultibyteStringConverter();
     }
 
     private function getSigner(): Ecdsa
@@ -50,7 +50,7 @@ private function getSigner(): Ecdsa
      *
      * @covers \Lcobucci\JWT\Signer\Ecdsa::sign
      * @covers \Lcobucci\JWT\Signer\Ecdsa::getKeyType
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      *
      * @uses \Lcobucci\JWT\Signer\Ecdsa::__construct
@@ -70,7 +70,7 @@ public function signShouldReturnTheAHashBasedOnTheOpenSslSignature(): void
             1,
             openssl_verify(
                 $payload,
-                $this->pointsManipulator->toEcPoint($signature, $signer->getKeyLength()),
+                $this->pointsManipulator->toAsn1($signature, $signer->getKeyLength()),
                 $publicKey,
                 OPENSSL_ALGO_SHA256
             )
@@ -82,7 +82,7 @@ public function signShouldReturnTheAHashBasedOnTheOpenSslSignature(): void
      *
      * @covers \Lcobucci\JWT\Signer\Ecdsa::verify
      * @covers \Lcobucci\JWT\Signer\Ecdsa::getKeyType
-     * @covers \Lcobucci\JWT\Signer\Ecdsa\Asn1
+     * @covers \Lcobucci\JWT\Signer\Ecdsa\MultibyteStringConverter
      * @covers \Lcobucci\JWT\Signer\OpenSSL
      *
      * @uses \Lcobucci\JWT\Signer\Ecdsa::__construct
@@ -102,7 +102,7 @@ public function verifyShouldDelegateToEcdsaSignerUsingPublicKey(): void
 
         self::assertTrue(
             $signer->verify(
-                $this->pointsManipulator->fromEcPoint($signature, $signer->getKeyLength()),
+                $this->pointsManipulator->fromAsn1($signature, $signer->getKeyLength()),
                 $payload,
                 self::$ecdsaKeys['public1']
             )