---
name: "libressl-EVP_PKEY_verify"
section: "3"
platform: "linux"
package: "libressl"
version: "4.4.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libressl-EVP_PKEY_verify"
---

# libressl-EVP\_PKEY\_verify(3)

signature verification using a public key algorithm

## NAME

**EVP\_PKEY\_verify\_init**, **EVP\_PKEY\_verify** – signature verification using a public key algorithm

## SYNOPSIS

Crypto Library (libcrypto, -lcrypto)

**#include \<openssl/evp.h\>**

*int*\

**EVP\_PKEY\_verify\_init**(*EVP\_PKEY\_CTX \*ctx*);

*int*\

**EVP\_PKEY\_verify**(*EVP\_PKEY\_CTX \*ctx*, *const unsigned char \*sig*, *size\_t siglen*, *const unsigned char \*tbs*, *size\_t tbslen*);

## DESCRIPTION

The **EVP\_PKEY\_verify\_init**() function initializes a public key algorithm context using key *ctx-\>pkey* for a signature verification operation.

The **EVP\_PKEY\_verify**() function performs a public key verification operation using *ctx*. The signature is specified using the *sig* and *siglen* parameters. The verified data (i.e. the data believed originally signed) is specified using the *tbs* and *tbslen* parameters.

After the call to **EVP\_PKEY\_verify\_init**(), algorithm specific control operations can be performed to set any appropriate parameters for the operation.

The function **EVP\_PKEY\_verify**() can be called more than once on the same context if several operations are performed using the same parameters.

## RETURN VALUES

**EVP\_PKEY\_verify\_init**() and **EVP\_PKEY\_verify**() return 1 if the verification was successful and 0 if it failed. Unlike other functions the return value 0 from **EVP\_PKEY\_verify**() only indicates that the signature did not verify successfully. That is, *tbs* did not match the original data or the signature was of invalid form. It is not an indication of a more serious error.

A negative value indicates an error other that signature verification failure. In particular, a return value of -2 indicates the operation is not supported by the public key algorithm.

## EXAMPLES

Verify signature using PKCS#1 and SHA-256 digest:

```
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
unsigned char *md, *sig;
size_t mdlen, siglen;
EVP_PKEY *verify_key;
/*
 * Assumes that verify_key, sig, siglen, md, and mdlen are already set up
 * and that verify_key is an RSA public key.
 */
ctx = EVP_PKEY_CTX_new(verify_key, NULL);
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 */
/* Perform operation */
ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
/*
 * ret == 1 indicates success, 0 verify failure,
 * and < 0 some other error.
 */
```

## SEE ALSO

EVP\_PKEY\_CTX\_new(3), EVP\_PKEY\_decrypt(3), EVP\_PKEY\_derive(3), EVP\_PKEY\_encrypt(3), EVP\_PKEY\_sign(3), EVP\_PKEY\_verify\_recover(3)

## HISTORY

**EVP\_PKEY\_verify\_init**() and **EVP\_PKEY\_verify**() first appeared in OpenSSL 1.0.0 and have been available since OpenBSD 4.9.