SubtleCrypto: verify() method
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Note: This feature is available in Web Workers.
The verify()
method of the SubtleCrypto
interface verifies a digital signature.
It takes as its arguments a key to verify the signature with, some algorithm-specific parameters, the signature, and the original signed data.
It returns a Promise
which will be fulfilled with a boolean value indicating whether the signature is valid.
Syntax
verify(algorithm, key, signature, data)
Parameters
algorithm
-
A string or object defining the algorithm to use, and for some algorithm choices, some extra parameters. The values given for the extra parameters must match those passed into the corresponding
sign()
call.- To use RSASSA-PKCS1-v1_5,
pass the string
"RSASSA-PKCS1-v1_5"
or an object of the form{ "name": "RSASSA-PKCS1-v1_5" }
. - To use RSA-PSS, pass an
RsaPssParams
object. - To use ECDSA, pass an
EcdsaParams
object. - To use HMAC, pass the string
"HMAC"
or an object of the form{ "name": "HMAC" }
. - To use Ed25519, pass an object of the form
{ "name": "Ed25519" }
.
- To use RSASSA-PKCS1-v1_5,
pass the string
key
-
A
CryptoKey
containing the key that will be used to verify the signature. It is the secret key for a symmetric algorithm and the public key for a public-key system. signature
-
A
ArrayBuffer
containing the signature to verify. data
-
A
ArrayBuffer
containing the data whose signature is to be verified.
Return value
A Promise
that fulfills with a
boolean value: true
if the signature is valid, false
otherwise.
Exceptions
The promise is rejected when the following exception is encountered:
InvalidAccessError
DOMException
-
Raised when the encryption key is not a key for the requested verifying algorithm or when trying to use an algorithm that is either unknown or isn't suitable for a verify operation.
Supported algorithms
The verify()
method supports the same algorithms as the sign()
method.
Examples
Note: You can try the working examples out on GitHub.
RSASSA-PKCS1-v1_5
This code uses a public key to verify a signature. See the complete code on GitHub.
/*
Fetch the contents of the "message" textbox, and encode it
in a form we can use for sign operation.
*/
function getMessageEncoding() {
const messageBox = document.querySelector(".rsassa-pkcs1 #message");
let message = messageBox.value;
let enc = new TextEncoder();
return enc.encode(message);
}
/*
Fetch the encoded message-to-sign and verify it against the stored signature.
* If it checks out, set the "valid" class on the signature.
* Otherwise set the "invalid" class.
*/
async function verifyMessage(publicKey) {
const signatureValue = document.querySelector(
".rsassa-pkcs1 .signature-value",
);
signatureValue.classList.remove("valid", "invalid");
let encoded = getMessageEncoding();
let result = await window.crypto.subtle.verify(
"RSASSA-PKCS1-v1_5",
publicKey,
signature,
encoded,
);
signatureValue.classList.add(result ? "valid" : "invalid");
}
RSA-PSS
This code uses a public key to verify a signature. See the complete code on GitHub.
/*
Fetch the contents of the "message" textbox, and encode it
in a form we can use for sign operation.
*/
function getMessageEncoding() {
const messageBox = document.querySelector(".rsa-pss #message");
let message = messageBox.value;
let enc = new TextEncoder();
return enc.encode(message);
}
/*
Fetch the encoded message-to-sign and verify it against the stored signature.
* If it checks out, set the "valid" class on the signature.
* Otherwise set the "invalid" class.
*/
async function verifyMessage(publicKey) {
const signatureValue = document.querySelector(".rsa-pss .signature-value");
signatureValue.classList.remove("valid", "invalid");
let encoded = getMessageEncoding();
let result = await window.crypto.subtle.verify(
{
name: "RSA-PSS",
saltLength: 32,
},
publicKey,
signature,
encoded,
);
signatureValue.classList.add(result ? "valid" : "invalid");
}
ECDSA
This code uses a public key to verify a signature. See the complete code on GitHub.
/*
Fetch the contents of the "message" textbox, and encode it
in a form we can use for sign operation.
*/
function getMessageEncoding() {
const messageBox = document.querySelector(".ecdsa #message");
let message = messageBox.value;
let enc = new TextEncoder();
return enc.encode(message);
}
/*
Fetch the encoded message-to-sign and verify it against the stored signature.
* If it checks out, set the "valid" class on the signature.
* Otherwise set the "invalid" class.
*/
async function verifyMessage(publicKey) {
const signatureValue = document.querySelector(".ecdsa .signature-value");
signatureValue.classList.remove("valid", "invalid");
let encoded = getMessageEncoding();
let result = await window.crypto.subtle.verify(
{
name: "ECDSA",
hash: { name: "SHA-384" },
},
publicKey,
signature,
encoded,
);
signatureValue.classList.add(result ? "valid" : "invalid");
}
HMAC
This code uses a secret key to verify a signature. See the complete code on GitHub.
/*
Fetch the contents of the "message" textbox, and encode it
in a form we can use for sign operation.
*/
function getMessageEncoding() {
const messageBox = document.querySelector(".hmac #message");
let message = messageBox.value;
let enc = new TextEncoder();
return enc.encode(message);
}
/*
Fetch the encoded message-to-sign and verify it against the stored signature.
* If it checks out, set the "valid" class on the signature.
* Otherwise set the "invalid" class.
*/
async function verifyMessage(key) {
const signatureValue = document.querySelector(".hmac .signature-value");
signatureValue.classList.remove("valid", "invalid");
let encoded = getMessageEncoding();
let result = await window.crypto.subtle.verify(
"HMAC",
key,
signature,
encoded,
);
signatureValue.classList.add(result ? "valid" : "invalid");
}
Ed25519
The Ed25519 live example in SubtleCrypto.sign()
shows how to generate public and private keys, use the private key to sign some data, and then use the public key to verify the signature.
The excerpt below shows the part that is relevant for verifying the signature using the public key and encoded data:
// Verify the signature using the public key
const verifyResult = await crypto.subtle.verify(
{
name: "Ed25519",
},
publicKey,
signature,
encodedData,
);
// True if the signature is valid.
Specifications
Specification |
---|
Web Cryptography API # SubtleCrypto-method-verify |
Browser compatibility
BCD tables only load in the browser
See also
SubtleCrypto.sign()
.- RFC 3447 specifies RSASSA-PKCS1-v1_5.
- RFC 3447 specifies RSA-PSS.
- FIPS-186 specifies ECDSA.
- FIPS 198-1 specifies HMAC.