[openssl-users] Openssl api for signature verification using digest

Wed Aug 29 05:05:00 UTC 2018

Thanks Viktor for the help….

Please find below the input format.

Still its not working.

> On Aug 28, 2018, at 7:08 AM, Linta Maria <lintamaria194 at gmail.com> wrote:
>
> I have used below code, but it’s not working. Please help me to get the
correct API.
>
> /*
>  * NB: assumes verify_key, sig, siglen md and mdlen are already set up
>  * and that verify_key is an RSA public key
>  */

In what form is the message digest?  Is it the raw digest octets,
or some hex or base64 encoding?  In what form is the signature?

Message digest  and signature is given in hex format.

Msg ={
0x8f,0x43,0x43,0x46,0x64,0x8f,0x6b,0x96,0xdf,0x89,0xdd,0xa9,0x1c,0x51,0x76,0xb1,0x0a,0x6d,0x83,0x96,0x1d,0xd3,0xc1,0xac,0x88,0xb5,0x9b,0x2d,0xc3,0x27,0xaa,0x4};

Signature={
0x24,0xb8,0xec,0xb4,0x4f,0x31,0xa6,0x8,0x72,0x61,0xc9,0xd3,0x1c,0xd0,0x9b,0xee,0x26,0x2d,0x3d,0xef,0xff,0x2c,0x5,0x78,0x4,0xd3,0xa3,0xff,0xdc,0x97,0x53,0xe6,0x6e,0x85,0x41,0x1b,0xb2,0x2c,0xed,0xbd,0xa6,0x5d,0x6f,0xac,0xbb,0xd5,0xb8,0xa0,0x9,0x2b,0xf1,0xf5,0xb6,0xce,0xdd,0x70,0x8a,0x1a,0xa1,0x20,0x11,0x2b,0xf0,0x17,0x41,0x83,0x80,0xf6,0x61,0xd4,0x6d,0x53,0x8f,0xf1,0x8c,0x19,0x42,0x93,0x96,0xa9,0xb6,0xf2,0x8f,0x27,0x9c,0x66,0x17,0xc5,0xca,0x3d,0xa9,0x3f,0xc5,0x76,0x5f,0x1b,0x31,0xf2,0xd3,0xe,0x78,0x53,0x97,0xcb,0x9d,0xc4,0xe6,0x41,0x61,0x58,0x44,0x5c,0xf5,0xc4,0x67,0x69,0x8,0xa,0x92,0xd5,0x7e,0x9c,0xb9,0x7e,0x54,0x8b,0x8a,0xb,0xa1,0x9a,0x63,0xbf,0xcc,0xed,0x63,0x2c,0xf8,0x14,0x25,0x6,0xa2,0x2,0x0,0x7,0x2e,0x1c,0xc1,0xeb,0x16,0x89,0xaa,0x69,0xe2,0x75,0x57,0x39,0x71,0x68,0xe,0xf,0xa4,0x7a,0xc5,0x14,0x97,0x88,0x67,0xd1,0x36,0x91,0x3b,0x49,0xe7,0xb4,0xf3,0xcb,0xca,0xf6,0xe9,0xb1,0x22,0xe9,0x85,0x89,0xab,0x2,0x4,0x3c,0x2e,0xbd,0x56,0x3,0x8a,0x8b,0x54,0xc6,0xe6,0xed,0x5b,0x4c,0xa4,0x9e,0x1b,0xaa,0x90,0xc6,0xb,0x27,0x54,0xc0,0x50,0x5f,0x58,0x97,0xc,0x99,0x5c,0x2,0x74,0xfc,0x9f,0x4c,0x78,0x4e,0xc3,0xb4,0x6d,0x14,0xa1,0xdc,0x62,0xc5,0xfe,0x27,0xb8,0x7d,0x98,0x79,0x82,0x50,0x3a,0xbe,0x6f,0x83,0x79,0xd,0x8a,0xb8,0x3e,0xac,0xa,0xeb,0x62,0xd5,0x5e,0x95}

PublicKey- In evp_pkey format

----BEGIN PUBLIC KEY-----

MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzMjyWZfVfBpmNKmIm9HH

FnrhDLZaCmQvZz57uJHhBLwLk/UAJ+kLKV9Lox8eKfimzisPFBad/TUfwPUaQmji

bPKCp+or2EHvPFooOnPWjSd57zPCohDdo0nOLw7iTUOMCvoqvJcdor+t1zBb8MQK

yNTycuoGlT19lr8msJFtR+ulfKucj/zk5w/jr0SsxysqFsvtEfa62Wu/wSDYIfsq

lKlRGLTlqJNtQybtTVv2Uu2KFrbe0C8+FBkxgtBS+0MkhzpJ37/02J+mHFx1bsgN

09QnQY+T05te+6/mmlsHP3PYRqXqJOLl9AkLd/9kiMhSFshowFehKmls9PYt1xGf

5QIDAQAB

-----END PUBLIC KEY-----

> ctx = EVP_PKEY_CTX_new(verify_key, NULL /* no engine */);
> if (!ctx)

>      /* Error occurred */
>
> if (EVP_PKEY_verify_init(ctx) <= 0)
>      /* Error */
>
> if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
>      /* Error */
>
> if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
>      /* Error */

Since you're verifying a hash, do not configure a message
digest.

> /* Perform operation */
>
> ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);

This is the right function for verifying public key
signatures over some input.  For more help, post
the *public* key used, the signature and the input
digest.

Message digest  and signature is given in hex format.

Msg ={
0x8f,0x43,0x43,0x46,0x64,0x8f,0x6b,0x96,0xdf,0x89,0xdd,0xa9,0x1c,0x51,0x76,0xb1,0x0a,0x6d,0x83,0x96,0x1d,0xd3,0xc1,0xac,0x88,0xb5,0x9b,0x2d,0xc3,0x27,0xaa,0x4};

Signature={
0x24,0xb8,0xec,0xb4,0x4f,0x31,0xa6,0x8,0x72,0x61,0xc9,0xd3,0x1c,0xd0,0x9b,0xee,0x26,0x2d,0x3d,0xef,0xff,0x2c,0x5,0x78,0x4,0xd3,0xa3,0xff,0xdc,0x97,0x53,0xe6,0x6e,0x85,0x41,0x1b,0xb2,0x2c,0xed,0xbd,0xa6,0x5d,0x6f,0xac,0xbb,0xd5,0xb8,0xa0,0x9,0x2b,0xf1,0xf5,0xb6,0xce,0xdd,0x70,0x8a,0x1a,0xa1,0x20,0x11,0x2b,0xf0,0x17,0x41,0x83,0x80,0xf6,0x61,0xd4,0x6d,0x53,0x8f,0xf1,0x8c,0x19,0x42,0x93,0x96,0xa9,0xb6,0xf2,0x8f,0x27,0x9c,0x66,0x17,0xc5,0xca,0x3d,0xa9,0x3f,0xc5,0x76,0x5f,0x1b,0x31,0xf2,0xd3,0xe,0x78,0x53,0x97,0xcb,0x9d,0xc4,0xe6,0x41,0x61,0x58,0x44,0x5c,0xf5,0xc4,0x67,0x69,0x8,0xa,0x92,0xd5,0x7e,0x9c,0xb9,0x7e,0x54,0x8b,0x8a,0xb,0xa1,0x9a,0x63,0xbf,0xcc,0xed,0x63,0x2c,0xf8,0x14,0x25,0x6,0xa2,0x2,0x0,0x7,0x2e,0x1c,0xc1,0xeb,0x16,0x89,0xaa,0x69,0xe2,0x75,0x57,0x39,0x71,0x68,0xe,0xf,0xa4,0x7a,0xc5,0x14,0x97,0x88,0x67,0xd1,0x36,0x91,0x3b,0x49,0xe7,0xb4,0xf3,0xcb,0xca,0xf6,0xe9,0xb1,0x22,0xe9,0x85,0x89,0xab,0x2,0x4,0x3c,0x2e,0xbd,0x56,0x3,0x8a,0x8b,0x54,0xc6,0xe6,0xed,0x5b,0x4c,0xa4,0x9e,0x1b,0xaa,0x90,0xc6,0xb,0x27,0x54,0xc0,0x50,0x5f,0x58,0x97,0xc,0x99,0x5c,0x2,0x74,0xfc,0x9f,0x4c,0x78,0x4e,0xc3,0xb4,0x6d,0x14,0xa1,0xdc,0x62,0xc5,0xfe,0x27,0xb8,0x7d,0x98,0x79,0x82,0x50,0x3a,0xbe,0x6f,0x83,0x79,0xd,0x8a,0xb8,0x3e,0xac,0xa,0xeb,0x62,0xd5,0x5e,0x95}

PublicKey- In evp_pkey format

----BEGIN PUBLIC KEY-----

MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzMjyWZfVfBpmNKmIm9HH

FnrhDLZaCmQvZz57uJHhBLwLk/UAJ+kLKV9Lox8eKfimzisPFBad/TUfwPUaQmji

bPKCp+or2EHvPFooOnPWjSd57zPCohDdo0nOLw7iTUOMCvoqvJcdor+t1zBb8MQK

yNTycuoGlT19lr8msJFtR+ulfKucj/zk5w/jr0SsxysqFsvtEfa62Wu/wSDYIfsq

lKlRGLTlqJNtQybtTVv2Uu2KFrbe0C8+FBkxgtBS+0MkhzpJ37/02J+mHFx1bsgN

09QnQY+T05te+6/mmlsHP3PYRqXqJOLl9AkLd/9kiMhSFshowFehKmls9PYt1xGf

5QIDAQAB

-----END PUBLIC KEY-----

You can find similar code in the source code of the
rsautl and pkeyutl commands.

-- 
        Viktor.

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