https://wiki.strongswan.org/projects/strongswan/wiki/IKEv1CipherSuites

IKEv1 Cipher Suites

The keywords listed below can be used with the ike and esp directives in ipsec.conf or the proposals settings in swanctl.conf to define cipher suites.

IANA provides lists of algorithm identifiers for IKEv1 and mp-registry" class="external" style="color: rgb(138, 0, 32); text-decoration-line: none; overflow-wrap: break-word; background-position: 0% 60%; background-repeat: no-repeat; padding-left: 12px; background-image: url("../images/external.png"); font-weight: bold;">IPsec.

Encryption Algorithms

Keyword	Description	IANA	IKE	ESP	Built-in Plugins	Deprecated
null	Null encryption	11		k
aes128 or aes	128 bit AES-CBC	7	x o g a	k	aes
aes192	192 bit AES-CBC		x o g a	k	aes
aes256	256 bit AES-CBC		x o g a	k	aes
aes128ctr	128 bit AES-COUNTER	13		k
aes192ctr	192 bit AES-COUNTER			k
aes256ctr	256 bit AES-COUNTER			k
aes128ccm8 or aes128ccm64	128 bit AES-CCM with 64 bit ICV	14		k
aes192ccm8 or aes192ccm64	192 bit AES-CCM with 64 bit ICV			k
aes256ccm8 or aes256ccm64	256 bit AES-CCM with 64 bit ICV			k
aes128ccm12 or aes128ccm96	128 bit AES-CCM with 96 bit ICV	15		k
aes192ccm12 or aes192ccm96	192 bit AES-CCM with 96 bit ICV			k
aes256ccm12 or aes256ccm96	256 bit AES-CCM with 96 bit ICV			k
aes128ccm16 or aes128ccm128	128 bit AES-CCM with 128 bit ICV	16		k
aes192ccm16 or aes192ccm128	192 bit AES-CCM with 128 bit ICV			k
aes256ccm16 or aes256ccm128	256 bit AES-CCM with 128 bit ICV			k
aes128gcm8 or aes128gcm64	128 bit AES-GCM with 64 bit ICV	18		k
aes192gcm8 or aes192gcm64	192 bit AES-GCM with 64 bit ICV			k
aes256gcm8 or aes256gcm64	256 bit AES-GCM with 64 bit ICV			k
aes128gcm12 or aes128gcm96	128 bit AES-GCM with 96 bit ICV	19		k
aes192gcm12 or aes192gcm96	192 bit AES-GCM with 96 bit ICV			k
aes256gcm12 or aes256gcm96	256 bit AES-GCM with 96 bit ICV			k
aes128gcm16 or aes128gcm128	128 bit AES-GCM with 128 bit ICV	20		k
aes192gcm16 or aes192gcm128	192 bit AES-GCM with 128 bit ICV			k
aes256gcm16 or aes256gcm128	256 bit AES-GCM with 128 bit ICV			k
aes128gmac	Null encryption with 128 bit AES-GMAC	23		k
aes192gmac	Null encryption with 192 bit AES-GMAC			k
aes256gmac	Null encryption with 256 bit AES-GMAC			k
3des	168 bit 3DES-EDE-CBC	5	x o g a	k	des	s
blowfish128 or blowfish	128 bit Blowfish-CBC	3	x o g a	k	blowfish	s
blowfish192	192 bit Blowfish-CBC		x o a	k	blowfish	s
blowfish256	256 bit Blowfish-CBC		x o a	k	blowfish	s
camellia128 or camellia	128 bit Camellia-CBC	8		k
camellia192	192 bit Camellia-CBC			k
camellia256	256 bit Camellia-CBC			k
serpent128 or serpent	128 bit Serpent-CBC	252	g a	k
serpent192	192 bit Serpent-CBC		g a	k
serpent256	256 bit Serpent-CBC		g a	k
twofish128 or twofish	128 bit Twofish-CBC	253	g a	k
twofish192	192 bit Twofish-CBC		a	k
twofish256	256 bit Twofish-CBC		g a	k
IKE support
x default built-in crypto plugin(s) (see separate column) o OpenSSL crypto library (openssl plugin) g Gcrypt crypto library (gcrypt plugin) a AF_ALG userland crypto API for Linux 2.6.38 kernel or newer (af-alg plugin)
ESP support
k Linux 2.6+ kernel
Deprecated
s broken by SWEET32

Integrity Algorithms

Keyword	Description	IANA	IKE	ESP/AH	Length	Built-in Plugins
md5	MD5 HMAC	1	x o a	k	96 bit	md5, hmac
sha1 or sha	SHA1 HMAC	2	x o a	k	96 bit	sha1, hmac
sha256 or sha2_256	SHA2_256_128 HMAC	5	x o a	n	128 bit	sha2, hmac
sha384 or sha2_384	SHA2_384_192 HMAC	6	x o a	k	192 bit	sha2, hmac
sha512 or sha2_512	SHA2_512_256 HMAC	7	x o a	k	256 bit	sha2, hmac
aesxcbc	AES XCBC	9		k	96 bit
aes128gmac	128-bit AES-GMAC	11		q	128 bit
aes192gmac	192-bit AES-GMAC	12		q	128 bit
aes256gmac	256-bit AES-GMAC	13		q	128 bit
IKE support
x default built-in crypto plugin(s) (see separate column) o OpenSSL crypto library (openssl plugin) a AF_ALG userland crypto API for Linux 2.6.38 kernel or newer (af-alg plugin) It's also possible to use the hash implementations provided by the gcrypt or openssl plugin together with the hmac plugin.
ESP/AH support
k Linux 2.6+ kernel q for AH, AES-GMAC is negotiated as encryption algorithm for ESP n before version 2.6.33 the Linux kernel incorrectly used 96 bit truncation for SHA-256

Diffie Hellman Groups

Keyword	DH Group	Modulus	Subgroup	IKE	Deprecated
Regular Groups
modp768	1	768 bits		m o g	l
modp1024	2	1024 bits		m o g	l
modp1536	5	1536 bits		m o g	l
modp2048	14	2048 bits		m o g
modp3072	15	3072 bits		m o g
modp4096	16	4096 bits		m o g
modp6144	17	6144 bits		m o g
modp8192	18	8192 bits		m o g
Modulo Prime Groups with Prime Order Subgroup
modp1024s160	22	1024 bits	160 bits	m o g	x
modp2048s224	23	2048 bits	224 bits	m o g	x
modp2048s256	24	2048 bits	256 bits	m o g	x
NIST Elliptic Curve Groups
ecp192	25	192 bits		o	w
ecp224	26	224 bits		o
ecp256	19	256 bits		o
ecp384	20	384 bits		o
ecp521	21	521 bits		o
Brainpool Elliptic Curve Groups
ecp224bp	27	224 bits		o
ecp256bp	28	256 bits		o
ecp384bp	29	384 bits		o
ecp512bp	30	512 bits		o
Elliptic Curve 25519 - only standardized for IKEv2 but also supported for IKEv1 by strongSwan
curve25519 or x25519	31	256 bits		c
IKE support
c curve25519 plugin m GMP multi-precision library (gmp plugin) o OpenSSL crypto library (openssl plugin) g Gcrypt crypto library (gcrypt plugin)
Deprecated
x questionable source of the primes. Potentially trapdoored (https://eprint.iacr.org/2016/961). l broken by LogJam w less than 112 bit security strength

Post-Quantum Key Exchange using NTRU Encryption

Keyword	DH Group	Strength	IKE
ntru112	1030	112 bits	n
ntru128	1031	128 bits	n
ntru192	1032	192 bits	n
ntru256	1033	256 bits	n
IKE support
n ntru plugin (includes ntru-crypto library)

Post-Quantum Key Exchange using NewHope

Keyword	DH Group	Strength	IKE
newhope128	1040	128 bits	n
IKE support
n newhope plugin

Since the Diffie-Hellman Group Transform IDs 1030..1033 and 1040 selected by the strongSwan project to designate the four NTRU key exchange strengths and the NewHope key exchange algorithm, respectively, were taken from the private-use range, the strongSwan vendor ID must be sent by the charon daemon. This can be enabled by the following statement in /etc/strongswan.conf: