/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*

 * Stuff specific to S/MIME policy and interoperability.

 */

#include "secmime.h"

#include "secoid.h"

#include "pk11func.h"

#include "ciferfam.h" /* for CIPHER_FAMILY symbols */

#include "secasn1.h"

#include "secitem.h"

#include "cert.h"

#include "keyhi.h"

#include "secerr.h"

#include "cms.h"

#include "nss.h"

SEC_ASN1_MKSUB(CERT_IssuerAndSNTemplate)

SEC_ASN1_MKSUB(SEC_OctetStringTemplate)

SEC_ASN1_CHOOSER_DECLARE(CERT_IssuerAndSNTemplate)

/* various integer's ASN.1 encoding */

static unsigned char asn1_int40[] = { SEC_ASN1_INTEGER, 0x01, 0x28 };

static unsigned char asn1_int64[] = { SEC_ASN1_INTEGER, 0x01, 0x40 };

static unsigned char asn1_int128[] = { SEC_ASN1_INTEGER, 0x02, 0x00, 0x80 };

/* RC2 algorithm parameters (used in smime_cipher_map) */

static SECItem param_int40 = { siBuffer, asn1_int40, sizeof(asn1_int40) };

static SECItem param_int64 = { siBuffer, asn1_int64, sizeof(asn1_int64) };

static SECItem param_int128 = { siBuffer, asn1_int128, sizeof(asn1_int128) };

/*

 * XXX Would like the "parameters" field to be a SECItem *, but the

 * encoder is having trouble with optional pointers to an ANY.  Maybe

 * once that is fixed, can change this back...

 */

typedef struct {

    SECItem capabilityID;

    SECItem parameters;

    long cipher; /* optimization */

} NSSSMIMECapability;

static const SEC_ASN1Template NSSSMIMECapabilityTemplate[] = {

    { SEC_ASN1_SEQUENCE,

      0, NULL, sizeof(NSSSMIMECapability) },

    { SEC_ASN1_OBJECT_ID,

      offsetof(NSSSMIMECapability, capabilityID) },

    { SEC_ASN1_OPTIONAL | SEC_ASN1_ANY,

      offsetof(NSSSMIMECapability, parameters) },

    { 0 }

};

static const SEC_ASN1Template NSSSMIMECapabilitiesTemplate[] = {

    { SEC_ASN1_SEQUENCE_OF, 0, NSSSMIMECapabilityTemplate }

};

/*

 * NSSSMIMEEncryptionKeyPreference - if we find one of these, it needs to prompt us

 *  to store this and only this certificate permanently for the sender email address.

 */

typedef enum {

    NSSSMIMEEncryptionKeyPref_IssuerSN,

    NSSSMIMEEncryptionKeyPref_RKeyID,

    NSSSMIMEEncryptionKeyPref_SubjectKeyID

} NSSSMIMEEncryptionKeyPrefSelector;

typedef struct {

    NSSSMIMEEncryptionKeyPrefSelector selector;

    union {

        CERTIssuerAndSN *issuerAndSN;

        NSSCMSRecipientKeyIdentifier *recipientKeyID;

        SECItem *subjectKeyID;

    } id;

} NSSSMIMEEncryptionKeyPreference;

extern const SEC_ASN1Template NSSCMSRecipientKeyIdentifierTemplate[];

static const SEC_ASN1Template smime_encryptionkeypref_template[] = {

    { SEC_ASN1_CHOICE,

      offsetof(NSSSMIMEEncryptionKeyPreference, selector), NULL,

      sizeof(NSSSMIMEEncryptionKeyPreference) },

    { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | SEC_ASN1_XTRN | 0 | SEC_ASN1_CONSTRUCTED,

      offsetof(NSSSMIMEEncryptionKeyPreference, id.issuerAndSN),

      SEC_ASN1_SUB(CERT_IssuerAndSNTemplate),

      NSSSMIMEEncryptionKeyPref_IssuerSN },

    { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | 1 | SEC_ASN1_CONSTRUCTED,

      offsetof(NSSSMIMEEncryptionKeyPreference, id.recipientKeyID),

      NSSCMSRecipientKeyIdentifierTemplate,

      NSSSMIMEEncryptionKeyPref_RKeyID },

    { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | SEC_ASN1_XTRN | 2 | SEC_ASN1_CONSTRUCTED,

      offsetof(NSSSMIMEEncryptionKeyPreference, id.subjectKeyID),

      SEC_ASN1_SUB(SEC_OctetStringTemplate),

      NSSSMIMEEncryptionKeyPref_SubjectKeyID },

    { 0 }

};

/* smime_cipher_map - map of SMIME symmetric "ciphers" to algtag & parameters */

typedef struct {

    unsigned long cipher;

    SECOidTag algtag;

    SECItem *parms;

    PRBool enabled; /* in the user's preferences */

    PRBool allowed; /* per export policy */

} smime_cipher_map_entry;

/* global: list of supported SMIME symmetric ciphers, ordered roughly by increasing strength */

static smime_cipher_map_entry smime_cipher_map[] = {

    /*    cipher, algtag, parms, enabled, allowed    */

    /*    ---------------------------------------    */

    { SMIME_RC2_CBC_40, SEC_OID_RC2_CBC, &param_int40, PR_TRUE, PR_TRUE },

    { SMIME_DES_CBC_56, SEC_OID_DES_CBC, NULL, PR_TRUE, PR_TRUE },

    { SMIME_RC2_CBC_64, SEC_OID_RC2_CBC, &param_int64, PR_TRUE, PR_TRUE },

    { SMIME_RC2_CBC_128, SEC_OID_RC2_CBC, &param_int128, PR_TRUE, PR_TRUE },

    { SMIME_DES_EDE3_168, SEC_OID_DES_EDE3_CBC, NULL, PR_TRUE, PR_TRUE },

    { SMIME_AES_CBC_128, SEC_OID_AES_128_CBC, NULL, PR_TRUE, PR_TRUE },

    { SMIME_AES_CBC_256, SEC_OID_AES_256_CBC, NULL, PR_TRUE, PR_TRUE }

};

static const int smime_cipher_map_count = sizeof(smime_cipher_map) / sizeof(smime_cipher_map_entry);

/*

 * smime_mapi_by_cipher - find index into smime_cipher_map by cipher

 */

static int

smime_mapi_by_cipher(unsigned long cipher)

{

    int i;

    for (i = 0; i < smime_cipher_map_count; i++) {

        if (smime_cipher_map[i].cipher == cipher)

            return i; /* bingo */

    }

    return -1; /* should not happen if we're consistent, right? */

}

/*

 * NSS_SMIME_EnableCipher - this function locally records the user's preference

 */

SECStatus

NSS_SMIMEUtil_EnableCipher(unsigned long which, PRBool on)

{

    unsigned long mask;

    int mapi;

    mask = which & CIPHER_FAMILYID_MASK;

    PORT_Assert(mask == CIPHER_FAMILYID_SMIME);

    if (mask != CIPHER_FAMILYID_SMIME)

        /* XXX set an error! */

        return SECFailure;

    mapi = smime_mapi_by_cipher(which);

    if (mapi < 0)

        /* XXX set an error */

        return SECFailure;

    /* do we try to turn on a forbidden cipher? */

    if (!smime_cipher_map[mapi].allowed && on) {

        PORT_SetError(SEC_ERROR_BAD_EXPORT_ALGORITHM);

        return SECFailure;

    }

    if (smime_cipher_map[mapi].enabled != on)

        smime_cipher_map[mapi].enabled = on;

    return SECSuccess;

}

/*

 * this function locally records the export policy

 */

SECStatus

NSS_SMIMEUtil_AllowCipher(unsigned long which, PRBool on)

{

    unsigned long mask;

    int mapi;

    mask = which & CIPHER_FAMILYID_MASK;

    PORT_Assert(mask == CIPHER_FAMILYID_SMIME);

    if (mask != CIPHER_FAMILYID_SMIME)

        /* XXX set an error! */

        return SECFailure;

    mapi = smime_mapi_by_cipher(which);

    if (mapi < 0)

        /* XXX set an error */

        return SECFailure;

    if (smime_cipher_map[mapi].allowed != on)

        smime_cipher_map[mapi].allowed = on;

    return SECSuccess;

}

/*

 * Based on the given algorithm (including its parameters, in some cases!)

 * and the given key (may or may not be inspected, depending on the

 * algorithm), find the appropriate policy algorithm specification

 * and return it.  If no match can be made, -1 is returned.

 */

static SECStatus

nss_smime_get_cipher_for_alg_and_key(SECAlgorithmID *algid, PK11SymKey *key,

                                     unsigned long *cipher)

{

    SECOidTag algtag;

    unsigned int keylen_bits;

    unsigned long c;

    algtag = SECOID_GetAlgorithmTag(algid);

    switch (algtag) {

        case SEC_OID_RC2_CBC:

            keylen_bits = PK11_GetKeyStrength(key, algid);

            switch (keylen_bits) {

                case 40:

                    c = SMIME_RC2_CBC_40;

                    break;

                case 64:

                    c = SMIME_RC2_CBC_64;

                    break;

                case 128:

                    c = SMIME_RC2_CBC_128;

                    break;

                default:

                    return SECFailure;

            }

            break;

        case SEC_OID_DES_CBC:

            c = SMIME_DES_CBC_56;

            break;

        case SEC_OID_DES_EDE3_CBC:

            c = SMIME_DES_EDE3_168;

            break;

        case SEC_OID_AES_128_CBC:

            c = SMIME_AES_CBC_128;

            break;

        case SEC_OID_AES_256_CBC:

            c = SMIME_AES_CBC_256;

            break;

        default:

            PORT_SetError(SEC_ERROR_INVALID_ALGORITHM);

            return SECFailure;

    }

    *cipher = c;

    return SECSuccess;

}

static PRBool

nss_smime_cipher_allowed(unsigned long which)

{

    int mapi;

    mapi = smime_mapi_by_cipher(which);

    if (mapi < 0)

        return PR_FALSE;

    return smime_cipher_map[mapi].allowed;

}

PRBool

NSS_SMIMEUtil_DecryptionAllowed(SECAlgorithmID *algid, PK11SymKey *key)

{

    unsigned long which;

    if (nss_smime_get_cipher_for_alg_and_key(algid, key, &which) != SECSuccess)

        return PR_FALSE;

    return nss_smime_cipher_allowed(which);

}

/*

 * NSS_SMIME_EncryptionPossible - check if any encryption is allowed

 *

 * This tells whether or not *any* S/MIME encryption can be done,

 * according to policy.  Callers may use this to do nicer user interface

 * (say, greying out a checkbox so a user does not even try to encrypt

 * a message when they are not allowed to) or for any reason they want

 * to check whether S/MIME encryption (or decryption, for that matter)

 * may be done.

 *

 * It takes no arguments.  The return value is a simple boolean:

 *   PR_TRUE means encryption (or decryption) is *possible*

 *      (but may still fail due to other reasons, like because we cannot

 *      find all the necessary certs, etc.; PR_TRUE is *not* a guarantee)

 *   PR_FALSE means encryption (or decryption) is not permitted

 *

 * There are no errors from this routine.

 */

PRBool

NSS_SMIMEUtil_EncryptionPossible(void)

{

    int i;

    for (i = 0; i < smime_cipher_map_count; i++) {

        if (smime_cipher_map[i].allowed)

            return PR_TRUE;

    }

    return PR_FALSE;

}

static int

nss_SMIME_FindCipherForSMIMECap(NSSSMIMECapability *cap)

{

    int i;

    SECOidTag capIDTag;

    /* we need the OIDTag here */

    capIDTag = SECOID_FindOIDTag(&(cap->capabilityID));

    /* go over all the SMIME ciphers we know and see if we find a match */

    for (i = 0; i < smime_cipher_map_count; i++) {

        if (smime_cipher_map[i].algtag != capIDTag)

            continue;

        /*

         * XXX If SECITEM_CompareItem allowed NULLs as arguments (comparing

         * 2 NULLs as equal and NULL and non-NULL as not equal), we could

         * use that here instead of all of the following comparison code.

         */

        if (!smime_cipher_map[i].parms) {

            if (!cap->parameters.data || !cap->parameters.len)

                break; /* both empty: bingo */

            if (cap->parameters.len == 2 &&

                cap->parameters.data[0] == SEC_ASN1_NULL &&

                cap->parameters.data[1] == 0)

                break; /* DER NULL == NULL, bingo */

        } else if (cap->parameters.data != NULL &&

                   cap->parameters.len == smime_cipher_map[i].parms->len &&

                   PORT_Memcmp(cap->parameters.data, smime_cipher_map[i].parms->data,

                               cap->parameters.len) == 0) {

            break; /* both not empty, same length & equal content: bingo */

        }

    }

    if (i == smime_cipher_map_count)

        return 0;                      /* no match found */

    return smime_cipher_map[i].cipher; /* match found, point to cipher */

}

/*

 * smime_choose_cipher - choose a cipher that works for all the recipients

 *

 * "scert"  - sender's certificate

 * "rcerts" - recipient's certificates

 */

static long

smime_choose_cipher(CERTCertificate *scert, CERTCertificate **rcerts)

{

    PLArenaPool *poolp;

    long cipher;

    long chosen_cipher;

    int *cipher_abilities;

    int *cipher_votes;

    int weak_mapi;

    int strong_mapi;

    int aes128_mapi;

    int aes256_mapi;

    int rcount, mapi, max, i;

    chosen_cipher = SMIME_RC2_CBC_40; /* the default, LCD */

    weak_mapi = smime_mapi_by_cipher(chosen_cipher);

    aes128_mapi = smime_mapi_by_cipher(SMIME_AES_CBC_128);

    aes256_mapi = smime_mapi_by_cipher(SMIME_AES_CBC_256);

    poolp = PORT_NewArena(1024); /* XXX what is right value? */

    if (poolp == NULL)

        goto done;

    cipher_abilities = (int *)PORT_ArenaZAlloc(poolp, smime_cipher_map_count * sizeof(int));

    cipher_votes = (int *)PORT_ArenaZAlloc(poolp, smime_cipher_map_count * sizeof(int));

    if (cipher_votes == NULL || cipher_abilities == NULL)

        goto done;

    /* Make triple-DES the strong cipher. */

    strong_mapi = smime_mapi_by_cipher(SMIME_DES_EDE3_168);

    /* walk all the recipient's certs */

    for (rcount = 0; rcerts[rcount] != NULL; rcount++) {

        SECItem *profile;

        NSSSMIMECapability **caps;

        int pref;

        /* the first cipher that matches in the user's SMIME profile gets

         * "smime_cipher_map_count" votes; the next one gets "smime_cipher_map_count" - 1

         * and so on. If every cipher matches, the last one gets 1 (one) vote */

        pref = smime_cipher_map_count;

        /* find recipient's SMIME profile */

        profile = CERT_FindSMimeProfile(rcerts[rcount]);

        if (profile != NULL && profile->data != NULL && profile->len > 0) {

            /* we have a profile (still DER-encoded) */

            caps = NULL;

            /* decode it */

            if (SEC_QuickDERDecodeItem(poolp, &caps,

                                       NSSSMIMECapabilitiesTemplate, profile) == SECSuccess &&

                caps != NULL) {

                /* walk the SMIME capabilities for this recipient */

                for (i = 0; caps[i] != NULL; i++) {

                    cipher = nss_SMIME_FindCipherForSMIMECap(caps[i]);

                    mapi = smime_mapi_by_cipher(cipher);

                    if (mapi >= 0) {

                        /* found the cipher */

                        cipher_abilities[mapi]++;

                        cipher_votes[mapi] += pref;

                        --pref;

                    }

                }

            }

        } else {

            /* no profile found - so we can only assume that the user can do

             * the mandatory algorithms which are RC2-40 (weak crypto) and

             * 3DES (strong crypto), unless the user has an elliptic curve

             * key.  For elliptic curve keys, RFC 5753 mandates support

             * for AES 128 CBC. */

            SECKEYPublicKey *key;

            unsigned int pklen_bits;

            KeyType key_type;

            /*

             * if recipient's public key length is > 512, vote for a strong cipher

             * please not that the side effect of this is that if only one recipient

             * has an export-level public key, the strong cipher is disabled.

             *

             * XXX This is probably only good for RSA keys.  What I would

             * really like is a function to just say;  Is the public key in

             * this cert an export-length key?  Then I would not have to

             * know things like the value 512, or the kind of key, or what

             * a subjectPublicKeyInfo is, etc.

             */

            key = CERT_ExtractPublicKey(rcerts[rcount]);

            pklen_bits = 0;

            key_type = nullKey;

            if (key != NULL) {

                pklen_bits = SECKEY_PublicKeyStrengthInBits(key);

                key_type = SECKEY_GetPublicKeyType(key);

                SECKEY_DestroyPublicKey(key);

                key = NULL;

            }

            if (key_type == ecKey) {

                /* While RFC 5753 mandates support for AES-128 CBC, should use

                 * AES 256 if user's key provides more than 128 bits of

                 * security strength so that symmetric key is not weak link. */

                /* RC2-40 is not compatible with elliptic curve keys. */

                chosen_cipher = SMIME_DES_EDE3_168;

                if (pklen_bits > 256) {

                    cipher_abilities[aes256_mapi]++;

                    cipher_votes[aes256_mapi] += pref;

                    pref--;

                }

                cipher_abilities[aes128_mapi]++;

                cipher_votes[aes128_mapi] += pref;

                pref--;

                cipher_abilities[strong_mapi]++;

                cipher_votes[strong_mapi] += pref;

                pref--;

            } else {

                if (pklen_bits > 512) {

                    /* cast votes for the strong algorithm */

                    cipher_abilities[strong_mapi]++;

                    cipher_votes[strong_mapi] += pref;

                    pref--;

                }

                /* always cast (possibly less) votes for the weak algorithm */

                cipher_abilities[weak_mapi]++;

                cipher_votes[weak_mapi] += pref;

            }

        }

        if (profile != NULL)

            SECITEM_FreeItem(profile, PR_TRUE);

    }

    /* find cipher that is agreeable by all recipients and that has the most votes */

    max = 0;

    for (mapi = 0; mapi < smime_cipher_map_count; mapi++) {

        /* if not all of the recipients can do this, forget it */

        if (cipher_abilities[mapi] != rcount)

            continue;

        /* if cipher is not enabled or not allowed by policy, forget it */

        if (!smime_cipher_map[mapi].enabled || !smime_cipher_map[mapi].allowed)

            continue;

        /* now see if this one has more votes than the last best one */

        if (cipher_votes[mapi] >= max) {

            /* if equal number of votes, prefer the ones further down in the list */

            /* with the expectation that these are higher rated ciphers */

            chosen_cipher = smime_cipher_map[mapi].cipher;

            max = cipher_votes[mapi];

        }

    }

/* if no common cipher was found, chosen_cipher stays at the default */

done:

    if (poolp != NULL)

        PORT_FreeArena(poolp, PR_FALSE);

    return chosen_cipher;

}

/*

 * XXX This is a hack for now to satisfy our current interface.

 * Eventually, with more parameters needing to be specified, just

 * looking up the keysize is not going to be sufficient.

 */

static int

smime_keysize_by_cipher(unsigned long which)

{

    int keysize;

    switch (which) {

        case SMIME_RC2_CBC_40:

            keysize = 40;

            break;

        case SMIME_RC2_CBC_64:

            keysize = 64;

            break;

        case SMIME_RC2_CBC_128:

        case SMIME_AES_CBC_128:

            keysize = 128;

            break;

        case SMIME_AES_CBC_256:

            keysize = 256;

            break;

        case SMIME_DES_CBC_56:

        case SMIME_DES_EDE3_168:

            /*

         * These are special; since the key size is fixed, we actually

         * want to *avoid* specifying a key size.

         */

            keysize = 0;

            break;

        default:

            keysize = -1;

            break;

    }

    return keysize;

}

/*

 * NSS_SMIMEUtil_FindBulkAlgForRecipients - find bulk algorithm suitable for all recipients

 *

 * it would be great for UI purposes if there would be a way to find out which recipients

 * prevented a strong cipher from being used...

 */

SECStatus

NSS_SMIMEUtil_FindBulkAlgForRecipients(CERTCertificate **rcerts,

                                       SECOidTag *bulkalgtag, int *keysize)

{

    unsigned long cipher;

    int mapi;

    cipher = smime_choose_cipher(NULL, rcerts);

    mapi = smime_mapi_by_cipher(cipher);

    *bulkalgtag = smime_cipher_map[mapi].algtag;

    *keysize = smime_keysize_by_cipher(smime_cipher_map[mapi].cipher);

    return SECSuccess;

}

/*

 * NSS_SMIMEUtil_CreateSMIMECapabilities - get S/MIME capabilities for this instance of NSS

 *

 * scans the list of allowed and enabled ciphers and construct a PKCS9-compliant

 * S/MIME capabilities attribute value.

 *

 * XXX Please note that, in contradiction to RFC2633 2.5.2, the capabilities only include

 * symmetric ciphers, NO signature algorithms or key encipherment algorithms.

 *

 * "poolp" - arena pool to create the S/MIME capabilities data on

 * "dest" - SECItem to put the data in

 */

SECStatus

NSS_SMIMEUtil_CreateSMIMECapabilities(PLArenaPool *poolp, SECItem *dest)

{

    NSSSMIMECapability *cap;

    NSSSMIMECapability **smime_capabilities;

    smime_cipher_map_entry *map;

    SECOidData *oiddata;

    SECItem *dummy;

    int i, capIndex;

    /* if we have an old NSSSMIMECapability array, we'll reuse it (has the right size) */

    /* smime_cipher_map_count + 1 is an upper bound - we might end up with less */

    smime_capabilities = (NSSSMIMECapability **)PORT_ZAlloc((smime_cipher_map_count + 1) * sizeof(NSSSMIMECapability *));

    if (smime_capabilities == NULL)

        return SECFailure;

    capIndex = 0;

    /* Add all the symmetric ciphers

     * We walk the cipher list backwards, as it is ordered by increasing strength,

     * we prefer the stronger cipher over a weaker one, and we have to list the

     * preferred algorithm first */

    for (i = smime_cipher_map_count - 1; i >= 0; i--) {

        /* Find the corresponding entry in the cipher map. */

        map = &(smime_cipher_map[i]);

        if (!map->enabled)

            continue;

        /* get next SMIME capability */

        cap = (NSSSMIMECapability *)PORT_ZAlloc(sizeof(NSSSMIMECapability));

        if (cap == NULL)

            break;

        smime_capabilities[capIndex++] = cap;

        oiddata = SECOID_FindOIDByTag(map->algtag);

        if (oiddata == NULL)

            break;

        cap->capabilityID.data = oiddata->oid.data;

        cap->capabilityID.len = oiddata->oid.len;

        cap->parameters.data = map->parms ? map->parms->data : NULL;

        cap->parameters.len = map->parms ? map->parms->len : 0;

        cap->cipher = smime_cipher_map[i].cipher;

    }

    /* XXX add signature algorithms */

    /* XXX add key encipherment algorithms */

    smime_capabilities[capIndex] = NULL; /* last one - now encode */

    dummy = SEC_ASN1EncodeItem(poolp, dest, &smime_capabilities, NSSSMIMECapabilitiesTemplate);

    /* now that we have the proper encoded SMIMECapabilities (or not),

     * free the work data */

    for (i = 0; smime_capabilities[i] != NULL; i++)

        PORT_Free(smime_capabilities[i]);

    PORT_Free(smime_capabilities);

    return (dummy == NULL) ? SECFailure : SECSuccess;

}

/*

 * NSS_SMIMEUtil_CreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value

 *

 * "poolp" - arena pool to create the attr value on

 * "dest" - SECItem to put the data in

 * "cert" - certificate that should be marked as preferred encryption key

 *          cert is expected to have been verified for EmailRecipient usage.

 */

SECStatus

NSS_SMIMEUtil_CreateSMIMEEncKeyPrefs(PLArenaPool *poolp, SECItem *dest, CERTCertificate *cert)

{

    NSSSMIMEEncryptionKeyPreference ekp;

    SECItem *dummy = NULL;

    PLArenaPool *tmppoolp = NULL;

    if (cert == NULL)

        goto loser;

    tmppoolp = PORT_NewArena(1024);

    if (tmppoolp == NULL)

        goto loser;

    /* XXX hardcoded IssuerSN choice for now */

    ekp.selector = NSSSMIMEEncryptionKeyPref_IssuerSN;

    ekp.id.issuerAndSN = CERT_GetCertIssuerAndSN(tmppoolp, cert);

    if (ekp.id.issuerAndSN == NULL)

        goto loser;

    dummy = SEC_ASN1EncodeItem(poolp, dest, &ekp, smime_encryptionkeypref_template);

loser:

    if (tmppoolp)

        PORT_FreeArena(tmppoolp, PR_FALSE);

    return (dummy == NULL) ? SECFailure : SECSuccess;

}

/*

 * NSS_SMIMEUtil_CreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value using MS oid

 *

 * "poolp" - arena pool to create the attr value on

 * "dest" - SECItem to put the data in

 * "cert" - certificate that should be marked as preferred encryption key

 *          cert is expected to have been verified for EmailRecipient usage.

 */

SECStatus

NSS_SMIMEUtil_CreateMSSMIMEEncKeyPrefs(PLArenaPool *poolp, SECItem *dest, CERTCertificate *cert)

{

    SECItem *dummy = NULL;

    PLArenaPool *tmppoolp = NULL;

    CERTIssuerAndSN *isn;

    if (cert == NULL)

        goto loser;

    tmppoolp = PORT_NewArena(1024);

    if (tmppoolp == NULL)

        goto loser;

    isn = CERT_GetCertIssuerAndSN(tmppoolp, cert);

    if (isn == NULL)

        goto loser;

    dummy = SEC_ASN1EncodeItem(poolp, dest, isn, SEC_ASN1_GET(CERT_IssuerAndSNTemplate));

loser:

    if (tmppoolp)

        PORT_FreeArena(tmppoolp, PR_FALSE);

    return (dummy == NULL) ? SECFailure : SECSuccess;

}

/*

 * NSS_SMIMEUtil_GetCertFromEncryptionKeyPreference -

 *                              find cert marked by EncryptionKeyPreference attribute

 *

 * "certdb" - handle for the cert database to look in

 * "DERekp" - DER-encoded value of S/MIME Encryption Key Preference attribute

 *

 * if certificate is supposed to be found among the message's included certificates,

 * they are assumed to have been imported already.

 */

CERTCertificate *

NSS_SMIMEUtil_GetCertFromEncryptionKeyPreference(CERTCertDBHandle *certdb, SECItem *DERekp)

{

    PLArenaPool *tmppoolp = NULL;

    CERTCertificate *cert = NULL;

    NSSSMIMEEncryptionKeyPreference ekp;

    tmppoolp = PORT_NewArena(1024);

    if (tmppoolp == NULL)

        return NULL;

    /* decode DERekp */

    if (SEC_QuickDERDecodeItem(tmppoolp, &ekp, smime_encryptionkeypref_template,

                               DERekp) != SECSuccess)

        goto loser;

    /* find cert */

    switch (ekp.selector) {

        case NSSSMIMEEncryptionKeyPref_IssuerSN:

            cert = CERT_FindCertByIssuerAndSN(certdb, ekp.id.issuerAndSN);

            break;

        case NSSSMIMEEncryptionKeyPref_RKeyID:

        case NSSSMIMEEncryptionKeyPref_SubjectKeyID:

            /* XXX not supported yet - we need to be able to look up certs by SubjectKeyID */

            break;

        default:

            PORT_Assert(0);

    }

loser:

    if (tmppoolp)

        PORT_FreeArena(tmppoolp, PR_FALSE);

    return cert;

}

extern const char __nss_smime_version[];

PRBool

NSSSMIME_VersionCheck(const char *importedVersion)

{

#define NSS_VERSION_VARIABLE __nss_smime_version

#include "verref.h"

    /*

     * This is the secret handshake algorithm.

     *

     * This release has a simple version compatibility

     * check algorithm.  This release is not backward

     * compatible with previous major releases.  It is

     * not compatible with future major, minor, or

     * patch releases.

     */

    return NSS_VersionCheck(importedVersion);

}

const char *

NSSSMIME_GetVersion(void)

{

    return NSS_VERSION;

}