A list of the crypto operations that we require, and what uses them.

This list is to allow research into using external crypto libraries.
Those possibly supported in the git version of GnuTLS are indicated as '# GNUTLS'
Those possibly supported in the git version of nettle are indicated as '# NETTLE'

For Samba AD with Heimdal gnutls >= 3.0.0 is required
For Samba AD with MIT kerberos gnutls >= 3.4.7 is required
Samba FS with MS Catalog support will require gnutls >= 3.5.6

GnuTLS Milestone for Samba support:
 - https://gitlab.com/gnutls/gnutls/milestones/14

ARCFOUR (RC4)
 - the old SamOEMHash
 - Password encryption on SAMR for password set/get
 - NETLOGON SamLogon session keys
 - Schannel
 - DRSUAPI replication replicated secrets

 # GNUTLS >= 3.0.0
 # NETTLE

DES
 - NTLM challenge-response
 - LSA QuerySecret et al
 - NETLOGON SamLogon session keys
 - ServerGetTrustInfo returned passwords
 - RID encryption of passwords

 # No support in gnutls, it cannot be a certified use of crypto
 # NETTLE (any version)

3DES
 - NETLOGON Credentials (can't find any use in Samba)

3DES-CBC
 - backupkey (uses heimdal lib or gnutls with mit krb5)

 # gnutls >= 3.4.7 (3des cbc with 192 bit key is supported); can no longer be a certified use of crypto
 # NETTLE

CRC32
 - DRSUAPI replication replicated secrets

This is no crypto

AES 128 in 8-bit CFB mode
 - SCHANNEL
 - NETLOGON SamLogon session keys

 # Missing in GNUTLS -> Bug opened
 # NETTLE 3.4 contains CFB - possibly 128-bit mode (AES-NI available)

AES128 CCM
 - SMB2 2.24 SMB encryption

 # GNUTLS >= 3.4.0
 # NETTLE (AES-NI available)

AES128 GCM
 - SMB2 3.10 SMB encryption
 - encrypted_secrets ldb module (encrypt secrets within sam.ldb)

 # GNUTLS >= 3.0.0
 # NETTLE (AES-NI available)

AES128 CMAC
 - SMB2 0x224 SMB Signing

 # Missing in GNUTLS - > Bug opened
 # Missing in NETTLE -> Bug opened

MD4
 - NTLM password hash

 # Cannot be certified; considered non-crypto
 # NETTLE

MD5
 - NTLM2 (can be considered non-crypto use of MD5)
 - SCHANNEL (it's ok to fail in FIPS140 mode, as there are alternatives)
 - NTLMSSP (it's ok to fail in FIPS140 mode, replaced by kerberos)
 - NETLOGON computer credentials (it's ok to fail in FIPS140 mode, as there are alternatives)
 - DRSUAPI blob encryption (can be considered non-crypto use as it is over DC-RPC which is encrypted)
 - SAMR/wkssvc password change/set encryption
 - vfs_fruit
 - vfs_streams_xattr
 - passdb old password history format
 - dsdb password_hash module
 - SMB1 SMB signing
 - NTP ntp_signd

maybe use gnutls_fips140_mode_enabled() and enable only SMB2/3 when in fips mode?

 # GNUTLS >= 3.0.0 (Will fail in FIPS mode, for non-crypto -> https://gitlab.com/gnutls/gnutls/merge_requests/572 , open bug for RC4, MD5 being available for non-crypto use )
 # NETTLE

HMAC-MD5
 - NTLMv2

 # GNUTLS >= 3.0.0 (non-crypto)
 # NETTLE

HMAC-SHA256
 - SMB2 < 2.24 SMB signing
 - SMB2 Key derivation

 # GNUTLS (>= 3.0.0)
 # NETTLE

HMAC-SHA1
 - BackupKey ServerWrap

 # GNUTLS (>= 3.0.0)
 # NETTLE

SHA256
 - Security Descriptor hash for vfs_acl_xattr
 - oLschema2ldif

 # GNUTLS (>= 3.0.0)
 # NETTLE

SHA512
 - SMB2 Pre-auth integrity verification
 - BackupKey ClientWrap

 # GNUTLS (>= 3.0.0)
 # NETTLE

RSA
 - BackupKey ClientWrap

 # GNUTLS (>= 3.0.0)
 # NETTLE


GNUTLS
Use gnutls_rnd() in generate_random_buffer() to increase speed