/*

 * Copyright 2019-2026 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/* Dispatch functions for gcm mode */

#include <openssl/rand.h>

#include <openssl/proverr.h>

#include "prov/ciphercommon.h"

#include "prov/ciphercommon_gcm.h"

#include "prov/providercommon.h"

#include "prov/provider_ctx.h"

#include "fips/fipsindicator.h"

#include "providers/implementations/ciphers/ciphercommon_gcm.inc"

static int gcm_tls_init(PROV_GCM_CTX *dat, unsigned char *aad, size_t aad_len);

static int gcm_tls_iv_set_fixed(PROV_GCM_CTX *ctx, unsigned char *iv,

    size_t len);

static int gcm_tls_cipher(PROV_GCM_CTX *ctx, unsigned char *out, size_t *padlen,

    const unsigned char *in, size_t len);

static int gcm_cipher_internal(PROV_GCM_CTX *ctx, unsigned char *out,

    size_t *padlen, const unsigned char *in,

    size_t len);

static int on_preupdate_generate_iv(PROV_GCM_CTX *ctx);

#ifdef FIPS_MODULE

static int gcm_fips_taglen_approved(size_t taglen)

{

    return taglen == UNINITIALISED_SIZET || taglen == 4 || taglen == 8

        || (taglen >= 12 && taglen <= GCM_TAG_MAX_SIZE);

}

#endif

/*

 * Called from EVP_CipherInit when there is currently no context via

 * the new_ctx() function

 */

void ossl_gcm_initctx(void *provctx, PROV_GCM_CTX *ctx, size_t keybits,

    const PROV_GCM_HW *hw)

{

    ctx->pad = 1;

    ctx->mode = EVP_CIPH_GCM_MODE;

    ctx->taglen = UNINITIALISED_SIZET;

    ctx->tls_aad_len = UNINITIALISED_SIZET;

    ctx->ivlen = (EVP_GCM_TLS_FIXED_IV_LEN + EVP_GCM_TLS_EXPLICIT_IV_LEN);

    ctx->keylen = keybits / 8;

    ctx->hw = hw;

    ctx->libctx = PROV_LIBCTX_OF(provctx);

}

/*

 * Called by EVP_CipherInit via the _einit and _dinit functions

 */

static int gcm_init(void *vctx, const unsigned char *key, size_t keylen,

    const unsigned char *iv, size_t ivlen,

    const OSSL_PARAM params[], int enc)

{

    PROV_GCM_CTX *ctx = (PROV_GCM_CTX *)vctx;

    if (!ossl_prov_is_running())

        return 0;

    ctx->enc = enc;

    if (iv != NULL) {

        if (ivlen == 0 || ivlen > sizeof(ctx->iv)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_IV_LENGTH);

            return 0;

        }

        ctx->iv_gen_rand = 0;

        ctx->ivlen = ivlen;

        memcpy(ctx->iv, iv, ivlen);

        ctx->iv_state = IV_STATE_BUFFERED;

    }

    if (key != NULL) {

        if (keylen != ctx->keylen) {

            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);

            return 0;

        }

        if (!ctx->hw->setkey(ctx, key, ctx->keylen))

            return 0;

        ctx->tls_enc_records = 0;

    }

    return ossl_gcm_set_ctx_params(ctx, params);

}

int ossl_gcm_einit(void *vctx, const unsigned char *key, size_t keylen,

    const unsigned char *iv, size_t ivlen,

    const OSSL_PARAM params[])

{

    return gcm_init(vctx, key, keylen, iv, ivlen, params, 1);

}

int ossl_gcm_dinit(void *vctx, const unsigned char *key, size_t keylen,

    const unsigned char *iv, size_t ivlen,

    const OSSL_PARAM params[])

{

    return gcm_init(vctx, key, keylen, iv, ivlen, params, 0);

}

/* increment counter (64-bit int) by 1 */

static void ctr64_inc(unsigned char *counter)

{

    int n = 8;

    unsigned char c;

    do {

        --n;

        c = counter[n];

        ++c;

        counter[n] = c;

        if (c > 0)

            return;

    } while (n > 0);

}

static int getivgen(PROV_GCM_CTX *ctx, unsigned char *out, size_t olen)

{

    if (!ctx->iv_gen

        || !ctx->key_set

        || !ctx->hw->setiv(ctx, ctx->iv, ctx->ivlen))

        return 0;

    if (olen == 0 || olen > ctx->ivlen)

        olen = ctx->ivlen;

    memcpy(out, ctx->iv + ctx->ivlen - olen, olen);

    /*

     * Invocation field will be at least 8 bytes in size and so no need

     * to check wrap around or increment more than last 8 bytes.

     */

    ctr64_inc(ctx->iv + ctx->ivlen - 8);

    ctx->iv_state = IV_STATE_COPIED;

    return 1;

}

static int setivinv(PROV_GCM_CTX *ctx, unsigned char *in, size_t inl)

{

    if (!ctx->iv_gen

        || !ctx->key_set

        || ctx->enc)

        return 0;

    memcpy(ctx->iv + ctx->ivlen - inl, in, inl);

    if (!ctx->hw->setiv(ctx, ctx->iv, ctx->ivlen))

        return 0;

    ctx->iv_state = IV_STATE_COPIED;

    return 1;

}

const OSSL_PARAM *ossl_gcm_gettable_ctx_params(

    ossl_unused void *cctx, ossl_unused void *provctx)

{

    return ossl_cipher_gcm_get_ctx_params_list;

}

int ossl_gcm_get_ctx_params(void *vctx, OSSL_PARAM params[])

{

    PROV_GCM_CTX *ctx = (PROV_GCM_CTX *)vctx;

    size_t sz;

    struct ossl_cipher_gcm_get_ctx_params_st p;

    if (ctx == NULL || !ossl_cipher_gcm_get_ctx_params_decoder(params, &p))

        return 0;

    if (p.ivlen != NULL && !OSSL_PARAM_set_size_t(p.ivlen, ctx->ivlen)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_SET_PARAMETER);

        return 0;

    }

    if (p.keylen != NULL && !OSSL_PARAM_set_size_t(p.keylen, ctx->keylen)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_SET_PARAMETER);

        return 0;

    }

    if (p.taglen != NULL) {

        size_t taglen = (ctx->taglen != UNINITIALISED_SIZET) ? ctx->taglen : GCM_TAG_MAX_SIZE;

        if (!OSSL_PARAM_set_size_t(p.taglen, taglen)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_SET_PARAMETER);

            return 0;

        }

    }

    /*

     * Note p.updiv and p.iv are aliases that get the same information,

     * so any code changes should be duplicated below.

     */

    if (p.iv != NULL) {

        if (!on_preupdate_generate_iv(ctx))

            return 0;

        if (p.iv->data != NULL && ctx->ivlen > p.iv->data_size) {

            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_IV_LENGTH);

            return 0;

        }

        if (!OSSL_PARAM_set_octet_string_or_ptr(p.iv, ctx->iv, ctx->ivlen)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_SET_PARAMETER);

            return 0;

        }

    }

    if (p.updiv != NULL) {

        if (!on_preupdate_generate_iv(ctx))

            return 0;

        if (p.updiv->data != NULL && ctx->ivlen > p.updiv->data_size) {

            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_IV_LENGTH);

            return 0;

        }

        if (!OSSL_PARAM_set_octet_string_or_ptr(p.updiv, ctx->iv, ctx->ivlen)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_SET_PARAMETER);

            return 0;

        }

    }

    if (p.pad != NULL && !OSSL_PARAM_set_size_t(p.pad, ctx->tls_aad_pad_sz)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_SET_PARAMETER);

        return 0;

    }

    if (p.tag != NULL) {

        if (!ctx->enc || ctx->taglen == UNINITIALISED_SIZET) {

            ERR_raise(ERR_LIB_PROV, PROV_R_TAG_NOT_SET);

            return 0;

        }

        if (p.tag->data == NULL) {

            /* size query: report the tag length, as for the iv above */

            sz = ctx->taglen;

        } else {

            sz = p.tag->data_size;

            if (sz > EVP_GCM_TLS_TAG_LEN || sz == 0) {

                ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_TAG);

                return 0;

            }

        }

        if (!OSSL_PARAM_set_octet_string(p.tag, ctx->buf, sz)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_SET_PARAMETER);

            return 0;

        }

    }

    if (p.ivgen != NULL)

        if (p.ivgen->data == NULL

            || p.ivgen->data_type != OSSL_PARAM_OCTET_STRING

            || !getivgen(ctx, p.ivgen->data, p.ivgen->data_size))

            return 0;

    if (p.gen != NULL && !OSSL_PARAM_set_uint(p.gen, ctx->iv_gen_rand))

        return 0;

    /*

     * Externally supplied IVs are permitted but not approved for encryption.

     * Approved tag lengths are 4, 8, and 12 through 16 bytes.

     * For encryption, requesting only a prefix of the generated tag does not

     * change the tag length used by the operation.

     */

    if (!OSSL_FIPS_IND_GET_PARAM_CONDITIONAL(p.ind,

            (!ctx->enc || ctx->iv_gen_rand)

                && gcm_fips_taglen_approved(ctx->taglen)))

        return 0;

    return 1;

}

const OSSL_PARAM *ossl_gcm_settable_ctx_params(

    ossl_unused void *cctx, ossl_unused void *provctx)

{

    return ossl_cipher_gcm_set_ctx_params_list;

}

int ossl_gcm_set_ctx_params(void *vctx, const OSSL_PARAM params[])

{

    PROV_GCM_CTX *ctx = (PROV_GCM_CTX *)vctx;

    size_t sz;

    void *vp;

    struct ossl_cipher_gcm_set_ctx_params_st p;

    if (ctx == NULL || !ossl_cipher_gcm_set_ctx_params_decoder(params, &p))

        return 0;

    if (p.tag != NULL) {

        vp = ctx->buf;

        if (!OSSL_PARAM_get_octet_string(p.tag, &vp, EVP_GCM_TLS_TAG_LEN, &sz)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);

            return 0;

        }

        if (ctx->enc) {

            ERR_raise(ERR_LIB_PROV, PROV_R_TAG_NOT_NEEDED);

            return 0;

        }

        if (sz == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_TAG);

            return 0;

        }

        ctx->taglen = sz;

    }

    if (p.ivlen != NULL) {

        if (!OSSL_PARAM_get_size_t(p.ivlen, &sz)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);

            return 0;

        }

        if (sz == 0 || sz > sizeof(ctx->iv)) {

            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_IV_LENGTH);

            return 0;

        }

        if (ctx->ivlen != sz) {

            /* If the iv was already set or autogenerated, it is invalid. */

            if (ctx->iv_state != IV_STATE_UNINITIALISED)

                ctx->iv_state = IV_STATE_FINISHED;

            ctx->ivlen = sz;

        }

    }

    if (p.aad != NULL) {

        if (p.aad->data_type != OSSL_PARAM_OCTET_STRING) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);

            return 0;

        }

        sz = gcm_tls_init(ctx, p.aad->data, p.aad->data_size);

        if (sz == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_AAD);

            return 0;

        }

        ctx->tls_aad_pad_sz = sz;

    }

    if (p.fixed != NULL) {

        if (p.fixed->data_type != OSSL_PARAM_OCTET_STRING) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);

            return 0;

        }

        if (gcm_tls_iv_set_fixed(ctx, p.fixed->data, p.fixed->data_size) == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);

            return 0;

        }

    }

    if (p.inviv != NULL)

        if (p.inviv->data == NULL

            || p.inviv->data_type != OSSL_PARAM_OCTET_STRING

            || !setivinv(ctx, p.inviv->data, p.inviv->data_size))

            return 0;

    return 1;

}

int ossl_gcm_stream_update(void *vctx, unsigned char *out, size_t *outl,

    size_t outsize, const unsigned char *in, size_t inl)

{

    PROV_GCM_CTX *ctx = (PROV_GCM_CTX *)vctx;

    if (inl == 0) {

        *outl = 0;

        return 1;

    }

    if (outsize < inl) {

        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);

        return 0;

    }

    if (gcm_cipher_internal(ctx, out, outl, in, inl) <= 0)

        return 0;

    return 1;

}

int ossl_gcm_stream_final(void *vctx, unsigned char *out, size_t *outl,

    size_t outsize)

{

    PROV_GCM_CTX *ctx = (PROV_GCM_CTX *)vctx;

    int i;

    if (!ossl_prov_is_running())

        return 0;

    i = gcm_cipher_internal(ctx, out, outl, NULL, 0);

    if (i <= 0)

        return 0;

    *outl = 0;

    return 1;

}

int ossl_gcm_cipher(void *vctx,

    unsigned char *out, size_t *outl, size_t outsize,

    const unsigned char *in, size_t inl)

{

    PROV_GCM_CTX *ctx = (PROV_GCM_CTX *)vctx;

    if (!ossl_prov_is_running())

        return 0;

    if (outsize < inl) {

        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);

        return 0;

    }

    if (gcm_cipher_internal(ctx, out, outl, in, inl) <= 0)

        return 0;

    *outl = inl;

    return 1;

}

/*

 * See SP800-38D (GCM) Section 8 "Uniqueness requirement on IVS and keys"

 *

 * See also 8.2.2 RBG-based construction.

 * Random construction consists of a free field (which can be NULL) and a

 * random field which will use a DRBG that can return at least 96 bits of

 * entropy strength. (The DRBG must be seeded by the FIPS module).

 */

static int gcm_iv_generate(PROV_GCM_CTX *ctx, int offset)

{

    int sz = (int)(ctx->ivlen - offset);

    /* Must be at least 96 bits */

    if (sz <= 0 || ctx->ivlen < GCM_IV_DEFAULT_SIZE)

        return 0;

    /* Use DRBG to generate random iv */

    if (RAND_bytes_ex(ctx->libctx, ctx->iv + offset, sz, 0) <= 0)

        return 0;

    ctx->iv_state = IV_STATE_BUFFERED;

    ctx->iv_gen_rand = 1;

    return 1;

}

/*

 * If we try to grab the iv before the update - it wont be generated yet,

 * so we generate it here for this case.

 */

static int on_preupdate_generate_iv(PROV_GCM_CTX *ctx)

{

    if (ctx->iv_state == IV_STATE_UNINITIALISED) {

        if (ctx->tls_aad_len != UNINITIALISED_SIZET)

            return 0;

        if (!ctx->enc || !gcm_iv_generate(ctx, 0))

            return 0;

    }

    return 1;

}

/* returns 1 on success, 0 on failure with a reason on the error queue */

static int gcm_cipher_internal(PROV_GCM_CTX *ctx, unsigned char *out,

    size_t *padlen, const unsigned char *in,

    size_t len)

{

    size_t olen = 0;

    int rv = 0;

    const PROV_GCM_HW *hw = ctx->hw;

    if (ctx->tls_aad_len != UNINITIALISED_SIZET)

        return gcm_tls_cipher(ctx, out, padlen, in, len);

    if (ctx->key_set == 0 || ctx->iv_state == IV_STATE_FINISHED) {

        ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

        goto err;

    }

    /*

     * FIPS requires generation of AES-GCM IV's inside the FIPS module.

     * The IV can still be set externally (the security policy will state that

     * this is not FIPS compliant). There are some applications

     * where setting the IV externally is the only option available.

     */

    if (ctx->iv_state == IV_STATE_UNINITIALISED) {

        if (ctx->enc == 0 || gcm_iv_generate(ctx, 0) == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

            goto err;

        }

    }

    if (ctx->iv_state == IV_STATE_BUFFERED) {

        if (hw->setiv(ctx, ctx->iv, ctx->ivlen) == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

            goto err;

        }

        ctx->iv_state = IV_STATE_COPIED;

    }

    if (in != NULL) {

        /*  The input is AAD if out is NULL */

        if (out == NULL) {

            int rv_aad = hw->aadupdate(ctx, in, len);

            if (rv_aad == -2) { /* AAD after payload */

                ERR_raise(ERR_LIB_PROV, PROV_R_UPDATE_CALL_OUT_OF_ORDER);

                goto err;

            }

            if (rv_aad <= 0) { /* AAD length overflow or other failure */

                ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

                goto err;

            }

        } else {

            /* The input is ciphertext OR plaintext */

            if (hw->cipherupdate(ctx, in, len, out) == 0) {

                ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

                goto err;

            }

        }

    } else {

        /* The tag must be set before actually decrypting data */

        if (!ctx->enc && ctx->taglen == UNINITIALISED_SIZET) {

            ERR_raise(ERR_LIB_PROV, PROV_R_TAG_NOT_SET);

            goto err;

        }

        if (hw->cipherfinal(ctx, ctx->buf) == 0) {

            if (ctx->enc == 0)

                ERR_raise(ERR_LIB_PROV, PROV_R_BAD_DECRYPT);

            else

                ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

            goto err;

        }

        ctx->iv_state = IV_STATE_FINISHED; /* Don't reuse the IV */

        goto finish;

    }

    olen = len;

finish:

    rv = 1;

err:

    *padlen = olen;

    return rv;

}

static int gcm_tls_init(PROV_GCM_CTX *dat, unsigned char *aad, size_t aad_len)

{

    unsigned char *buf;

    size_t len;

    if (!ossl_prov_is_running() || aad_len != EVP_AEAD_TLS1_AAD_LEN)

        return 0;

    /* Save the aad for later use. */

    buf = dat->buf;

    memcpy(buf, aad, aad_len);

    dat->tls_aad_len = aad_len;

    len = buf[aad_len - 2] << 8 | buf[aad_len - 1];

    /* Correct length for explicit iv. */

    if (len < EVP_GCM_TLS_EXPLICIT_IV_LEN)

        return 0;

    len -= EVP_GCM_TLS_EXPLICIT_IV_LEN;

    /* If decrypting correct for tag too. */

    if (!dat->enc) {

        if (len < EVP_GCM_TLS_TAG_LEN)

            return 0;

        len -= EVP_GCM_TLS_TAG_LEN;

    }

    buf[aad_len - 2] = (unsigned char)(len >> 8);

    buf[aad_len - 1] = (unsigned char)(len & 0xff);

    /* Extra padding: tag appended to record. */

    return EVP_GCM_TLS_TAG_LEN;

}

static int gcm_tls_iv_set_fixed(PROV_GCM_CTX *ctx, unsigned char *iv,

    size_t len)

{

    /* Special case: -1 length restores whole IV */

    if (len == (size_t)-1) {

        memcpy(ctx->iv, iv, ctx->ivlen);

        ctx->iv_gen_rand = 0;

        ctx->iv_gen = 1;

        ctx->iv_state = IV_STATE_BUFFERED;

        return 1;

    }

    /* Fixed field must be at least 4 bytes and invocation field at least 8 */

    if (len < EVP_GCM_TLS_FIXED_IV_LEN

        || len > ctx->ivlen

        || (ctx->ivlen - len) < EVP_GCM_TLS_EXPLICIT_IV_LEN)

        return 0;

    if (len > 0)

        memcpy(ctx->iv, iv, len);

    if (ctx->enc) {

        if (RAND_bytes_ex(ctx->libctx, ctx->iv + len, ctx->ivlen - len, 0) <= 0)

            return 0;

        ctx->iv_gen_rand = 1;

    }

    ctx->iv_gen = 1;

    ctx->iv_state = IV_STATE_BUFFERED;

    return 1;

}

/*

 * Handle TLS GCM packet format. This consists of the last portion of the IV

 * followed by the payload and finally the tag. On encrypt generate IV,

 * encrypt payload and write the tag. On verify retrieve IV, decrypt payload

 * and verify tag.

 */

static int gcm_tls_cipher(PROV_GCM_CTX *ctx, unsigned char *out, size_t *padlen,

    const unsigned char *in, size_t len)

{

    int rv = 0;

    size_t arg = EVP_GCM_TLS_EXPLICIT_IV_LEN;

    size_t plen = 0;

    unsigned char *tag = NULL;

    if (ossl_prov_is_running() == 0 || ctx->key_set == 0) {

        ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

        goto err;

    }

    /* Encrypt/decrypt must be performed in place */

    if (out != in || len < (EVP_GCM_TLS_EXPLICIT_IV_LEN + EVP_GCM_TLS_TAG_LEN)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

        goto err;

    }

    /*

     * Check for too many keys as per FIPS 140-2 IG A.5 "Key/IV Pair Uniqueness

     * Requirements from SP 800-38D".  The requirements is for one party to the

     * communication to fail after 2^64 - 1 keys.  We do this on the encrypting

     * side only.

     */

    if (ctx->enc && ++ctx->tls_enc_records == 0) {

        ERR_raise(ERR_LIB_PROV, PROV_R_TOO_MANY_RECORDS);

        goto err;

    }

    /*

     * Set IV from start of buffer or generate IV and write to start of

     * buffer.

     */

    if (ctx->enc) {

        if (getivgen(ctx, out, arg) == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

            goto err;

        }

    } else {

        if (setivinv(ctx, out, arg) == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

            goto err;

        }

    }

    /* Fix buffer and length to point to payload */

    in += EVP_GCM_TLS_EXPLICIT_IV_LEN;

    out += EVP_GCM_TLS_EXPLICIT_IV_LEN;

    len -= EVP_GCM_TLS_EXPLICIT_IV_LEN + EVP_GCM_TLS_TAG_LEN;

    tag = ctx->enc ? out + len : (unsigned char *)in + len;

    if (!ctx->hw->oneshot(ctx, ctx->buf, ctx->tls_aad_len, in, len, out, tag,

            EVP_GCM_TLS_TAG_LEN)) {

        if (!ctx->enc)

            OPENSSL_cleanse(out, len);

        ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);

        goto err;

    }

    if (ctx->enc)

        plen = len + EVP_GCM_TLS_EXPLICIT_IV_LEN + EVP_GCM_TLS_TAG_LEN;

    else

        plen = len;

    rv = 1;

err:

    ctx->iv_state = IV_STATE_FINISHED;

    ctx->tls_aad_len = UNINITIALISED_SIZET;

    *padlen = plen;

    return rv;

}