CODEWITHSUNDEEP
node.jsopensslcryptojs
Amit Rana
Amit Rana

Reputation: 43

Crypto RSASSA-PSS algo in node.js

I am using crypto. I have public key, data and signature. All working fine with openssl command

openssl dgst -sha256 -sigopt rsa_padding_mode:pss -verify pk.pem -signature sigval1.sig data1.txt

But while using node crypto verify it always returning false

crypto.verify(
    'RSA-SHA256',
    Buffer.from(data),
    newPublicKey,
    Buffer.from(signature, 'binary'),
  )

Requirement: "alg": "RSASSA-PSS","hash": "SHA256"

Upvotes: 1

Views: 1173

Answers (1)

Topaco
Topaco

Reputation: 49131

In the OpenSSL statement, PSS is used as padding. NodeJS applies PKCS#1 v1.5 padding by default, so PSS must be explicitly specified in the third parameter in crypto.verify(...):

var verified = crypto.verify(
    'RSA-SHA256',
    Buffer.from(data, 'utf-8'),
    {
        key: newPublicKey, 
        padding: crypto.constants.RSA_PKCS1_PSS_PADDING,
        //saltLength: crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN // default
    },
    Buffer.from(signature, 'binary')
);

Note that the OpenSSL statement uses the maximum possible salt length as the salt length, rather than the default given in RFC8017, which is the output length of the digest. This is not critical here in that crypto.verify() also uses the maximum salt length (crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN).

Upvotes: 1

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