From 779a850e0fb967aac79124c7e18b14706d5f2652 Mon Sep 17 00:00:00 2001
From: Frank Denis
Date: Tue, 25 Feb 2025 15:03:50 +0100
Subject: Add optional support for AEGIS encryption

AEGIS is a new family of authenticated encryption algorithms that offers
stronger security, higher usage limits, and better performance than AES-GCM.

This pull request adds support for a new `-aegis` command-line flag, allowing
AEGIS-128X2 to be used as an alternative to AES-GCM on CPUs with AES acceleration.

It also introduces the ability to use ciphers with different key sizes.

More information on AEGIS is available here:
- https://cfrg.github.io/draft-irtf-cfrg-aegis-aead/draft-irtf-cfrg-aegis-aead.html
- https://github.com/cfrg/draft-irtf-cfrg-aegis-aead

gocryptfs -speed speed on Apple M1:

AES-GCM-256-OpenSSL              3718.79 MB/s
AES-GCM-256-Go                   5083.43 MB/s   (selected in auto mode)
AES-SIV-512-Go                    625.20 MB/s
XChaCha20-Poly1305-OpenSSL       1358.63 MB/s   (selected in auto mode)
XChaCha20-Poly1305-Go             832.11 MB/s
Aegis128X2-Go                   11818.73 MB/s

gocryptfs -speed speed on AMD Zen 4:

AES-GCM-256-OpenSSL              5215.86 MB/s
AES-GCM-256-Go                   6918.01 MB/s   (selected in auto mode)
AES-SIV-512-Go                    449.61 MB/s
XChaCha20-Poly1305-OpenSSL       2643.48 MB/s
XChaCha20-Poly1305-Go            3727.46 MB/s   (selected in auto mode)
Aegis128X2-Go                   28109.92 MB/s
---
 internal/configfile/validate.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'internal/configfile/validate.go')

diff --git a/internal/configfile/validate.go b/internal/configfile/validate.go
index ab8917d..333eea6 100644
--- a/internal/configfile/validate.go
+++ b/internal/configfile/validate.go
@@ -38,8 +38,13 @@ func (cf *ConfFile) Validate() error {
 				return fmt.Errorf("XChaCha20Poly1305 requires HKDF feature flag")
 			}
 		}
+		if cf.IsFeatureFlagSet(FlagAegis) {
+			if cf.IsFeatureFlagSet(FlagGCMIV128) {
+				return fmt.Errorf("AEGIS conflicts with GCMIV128 feature flag")
+			}
+		}
 		// The absence of other flags means AES-GCM (oldest algorithm)
-		if !cf.IsFeatureFlagSet(FlagXChaCha20Poly1305) && !cf.IsFeatureFlagSet(FlagAESSIV) {
+		if !cf.IsFeatureFlagSet(FlagAegis) && !cf.IsFeatureFlagSet(FlagXChaCha20Poly1305) && !cf.IsFeatureFlagSet(FlagAESSIV) {
 			if !cf.IsFeatureFlagSet(FlagGCMIV128) {
 				return fmt.Errorf("AES-GCM requires GCMIV128 feature flag")
 			}
-- 
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