int
EVP_CIPHER_CTX_get_iv(const EVP_CIPHER_CTX *ctx, unsigned char *iv, size_t len)
{
    if (ctx == NULL || len != EVP_CIPHER_CTX_iv_length(ctx))
        return 0;
    if (len > EVP_MAX_IV_LENGTH)
        return 0; /* sanity check; shouldn't happen */
    /*
     * Skip the memcpy entirely when the requested IV length is zero,
     * since the iv pointer may be NULL or invalid.
     */
    if (len != 0) {
        if (iv == NULL)
            return 0;
        memcpy(iv, ctx->iv, len);
    }
    return 1;
}

int
EVP_CIPHER_CTX_set_iv(EVP_CIPHER_CTX *ctx, const unsigned char *iv, size_t len)
{
    if (ctx == NULL || len != EVP_CIPHER_CTX_iv_length(ctx))
        return 0;
    if (len > EVP_MAX_IV_LENGTH)
        return 0; /* sanity check; shouldn't happen */
    /*
     * Skip the memcpy entirely when the requested IV length is zero,
     * since the iv pointer may be NULL or invalid.
     */
    if (len != 0) {
        if (iv == NULL)
            return 0;
        memcpy(ctx->iv, iv, len);
    }
    return 1;
}