RFC 4568 – Security Descriptions for Media Streams

RFC 4568 – Section 9 — see also: IANA

a=crypto

attribute-fields =/

crypto-attr

crypto-attr =

"a=crypto:" tag 1*WSP crypto-suite 1*WSP key-params *( 1*WSP session-param ) CRLF

tag =

1*9DIGIT

crypto-suite =

1*( ALPHA / DIGIT / "_" )

key-params =

key-param *( ";" key-param )

key-param =

key-method ":" key-info

key-method =

"inline" / key-method-ext

key-method-ext =

1*( ALPHA / DIGIT / "_" )

key-info =

1*( %x21-3A / %x3C-7E )
; visible (printing) chars except semi-colon

session-param =

1*( VCHAR )
; visible (printing) chars

Grammar for SRTP transport

RFC 4568 – Section 9.2

IANA SRTP Crypto Suite Registrations

IANA Media Stream Transports

IANA SRTP Session Parameters

crypto-suite =

srtp-crypto-suite

key-method =

srtp-key-method

key-info =

srtp-key-info

session-param =

srtp-session-param

srtp-crypto-suite =

"AES_CM_128_HMAC_SHA1_32" / ; see RFC 4568
"F8_128_HMAC_SHA1_32" / ; see RFC 4568
"AES_CM_128_HMAC_SHA1_80" / ; see RFC 4568
"SEED_CTR_128_HMAC_SHA1_80" / ; see RFC 5669 – Section 7
"SEED_128_CCM_80" / ; see RFC 5669
"SEED_128_GCM_96" / ; see RFC 5669
"AES_192_CM_HMAC_SHA1_80" / ; see RFC 6188 – Section 5
"AES_192_CM_HMAC_SHA1_32" / ; see RFC 6188
"AES_256_CM_HMAC_SHA1_80" / ; see RFC 6188
"AES_256_CM_HMAC_SHA1_32" / ; see RFC 6188
"AEAD_AES_128_GCM" / ; see RFC 7714 – Section 14.1
"AEAD_AES_256_GCM" / ; see RFC 7714
srtp-crypto-suite-ext

srtp-key-method =

"inline"

srtp-key-info =

key-salt [ "|" lifetime ] [ "|" mki ]

key-salt =

1*( base64 )
; binary key and salt values concatenated together, and then
; base64 encoded [RFC 4648 – Section 4]

lifetime =

[ "2^" ] 1*( DIGIT )

mki =

mki-value ":" mki-length

mki-value =

1*DIGIT