ERR_OSSL_EVP_UNSUPPORTED

The ERR_OSSL_EVP_UNSUPPORTED error code is produced by the OpenSSL library when an operation is not supported by the cryptographic algorithm or function.

Description

When using OpenSSL library for cryptographic operations, ERR_OSSL_EVP_UNSUPPORTED error can occur when an unsupported operation is attempted on a cryptographic algorithm or function. This error occurs when the requested operation is incompatible with the underlying cryptographic algorithm.

Causes

• The cryptographic function or algorithm being used doesn't support the requested operation.
• The OpenSSL library version may not support the requested feature.
• The input data is not properly formed or is of an incorrect type.

Resolutions

• Verify that the cryptographic function or algorithm supports the operation.
• Check the OpenSSL library version to ensure that the requested feature is supported.
• Ensure that the input data is correctly formatted and of the correct type.

Example

Suppose a program tries to encrypt data using an unsupported algorithm:

EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
if (!ctx) {
    //handle error...
}
if (EVP_EncryptInit_ex(ctx, EVP_camellia_128_cbc(), NULL, key, iv) != 1) {
    //handle error...
}
if (EVP_EncryptUpdate(ctx, output, &outlen, input, inlen) != 1) {
    //handle error...
}
if (EVP_EncryptFinal_ex(ctx, output + outlen, &tmplen) != 1) {
    //handle error...
}

In this case, if the EVP_camellia_128_cbc() function is not supported, an ERR_OSSL_EVP_UNSUPPORTED error will be returned. Hence, it is essential to verify that the requested algorithm or function is supported before using it.

Conclusion

ERR_OSSL_EVP_UNSUPPORTED error in OpenSSL library can be caused by various factors, including unsupported cryptographic algorithms or functions, incompatible OpenSSL library version, or incorrect input data types. By verifying that the proper requirements are in place, developers can mitigate and handle such errors effectively.