Reduce allocations in encrypt/decrypt RTP #355

thesyncim · 2025-12-19T17:56:37Z

goarch: arm64                                                                                                                                                                                                        
pkg: github.com/pion/srtp/v3                                                                                                                                                                                         
cpu: Apple M2 Pro                                                                                                                                                                                                    
                              │ bench_old.txt │            bench_new.txt            │                                                                                                                                
                              │    sec/op     │    sec/op     vs base               │                                                                                                                                
EncryptRTP/CTR-100-10            385.3n ±  8%   354.1n ±  6%   -8.11% (p=0.002 n=6)                                                                                                                                  
EncryptRTP/CTR-1000-10           1.574µ ±  4%   1.558µ ±  6%        ~ (p=0.366 n=6)                                                                                                                                  
EncryptRTP/GCM-100-10            247.7n ±  9%   211.2n ±  6%  -14.76% (p=0.002 n=6)                                                                                                                                  
EncryptRTP/GCM-1000-10           510.6n ±  7%   482.2n ± 15%        ~ (p=0.310 n=6)                                                                                                                                  
EncryptRTPInPlace/CTR-100-10     363.0n ± 22%   336.7n ±  1%   -7.23% (p=0.002 n=6)                                                                                                                                  
EncryptRTPInPlace/CTR-1000-10    1.378µ ±  8%   1.369µ ±  9%        ~ (p=0.589 n=6)                                                                                                                                  
EncryptRTPInPlace/GCM-100-10     199.0n ± 24%   183.3n ±  4%   -7.89% (p=0.002 n=6)                                                                                                                                  
EncryptRTPInPlace/GCM-1000-10    352.2n ± 11%   305.6n ±  8%  -13.23% (p=0.015 n=6)                                                                                                                                  
DecryptRTP/CTR-10                286.2n ±  5%   262.8n ±  3%   -8.19% (p=0.002 n=6)                                                                                                                                  
DecryptRTP/GCM-10                168.2n ± 44%   151.3n ±  4%  -10.05% (p=0.002 n=6)                                                                                                                                  
geomean                          408.5n         376.8n         -7.77%                                                                                                                                                
                                                                                                                                                                                                                     
                              │ bench_old.txt │             bench_new.txt             │                                                                                                                              
                              │      B/s      │      B/s        vs base               │                                                                                                                              
EncryptRTP/CTR-100-10           277.2Mi ±  7%    301.7Mi ±  6%   +8.80% (p=0.002 n=6)                                                                                                                                
EncryptRTP/CTR-1000-10          613.6Mi ±  4%    619.9Mi ±  6%        ~ (p=0.372 n=6)                                                                                                                                
EncryptRTP/GCM-100-10           431.3Mi ± 10%    505.8Mi ±  6%  +17.26% (p=0.002 n=6)                                                                                                                                
EncryptRTP/GCM-1000-10          1.846Gi ±  6%    1.955Gi ± 13%        ~ (p=0.310 n=6)                                                                                                                                
EncryptRTPInPlace/CTR-100-10    294.3Mi ± 18%    317.3Mi ±  1%   +7.81% (p=0.002 n=6)                                                                                                                                
EncryptRTPInPlace/CTR-1000-10   700.4Mi ±  7%    705.1Mi ±  9%        ~ (p=0.589 n=6)                                                                                                                                
EncryptRTPInPlace/GCM-100-10    537.0Mi ± 19%    582.7Mi ±  4%   +8.52% (p=0.002 n=6)                                                                                                                                
EncryptRTPInPlace/GCM-1000-10   2.676Gi ± 12%    3.084Gi ±  7%  +15.25% (p=0.015 n=6)                                                                                                                                
DecryptRTP/CTR-10               93.29Mi ±  5%   101.60Mi ±  3%   +8.91% (p=0.002 n=6)                                                                                                                                
DecryptRTP/GCM-10               192.9Mi ± 31%    214.3Mi ±  4%  +11.10% (p=0.002 n=6)                                                                                                                                
geomean                         487.4Mi          528.4Mi         +8.41%                                                                                                                                              
                                                                                                                                                                                                                     
                              │ bench_old.txt │            bench_new.txt            │                                                                                                                                
                              │     B/op      │     B/op      vs base               │                                                                                                                                
EncryptRTP/CTR-100-10              252.0 ± 0%     224.0 ± 0%  -11.11% (p=0.002 n=6)                                                                                                                                  
EncryptRTP/CTR-1000-10           1.121Ki ± 0%   1.094Ki ± 0%   -2.44% (p=0.002 n=6)                                                                                                                                  
EncryptRTP/GCM-100-10              240.0 ± 0%     224.0 ± 0%   -6.67% (p=0.002 n=6)                                                                                                                                  
EncryptRTP/GCM-1000-10           1.234Ki ± 0%   1.219Ki ± 0%   -1.27% (p=0.002 n=6)                                                                                                                                  
EncryptRTPInPlace/CTR-100-10      124.00 ± 0%     96.00 ± 0%  -22.58% (p=0.002 n=6)                                                                                                                                  
EncryptRTPInPlace/CTR-1000-10     124.00 ± 0%     96.00 ± 0%  -22.58% (p=0.002 n=6)                                                                                                                                  
EncryptRTPInPlace/GCM-100-10      112.00 ± 0%     96.00 ± 0%  -14.29% (p=0.002 n=6)                                                                                                                                  
EncryptRTPInPlace/GCM-1000-10     112.00 ± 0%     96.00 ± 0%  -14.29% (p=0.002 n=6)                                                                                                                                  
DecryptRTP/CTR-10                  148.0 ± 0%     120.0 ± 0%  -18.92% (p=0.002 n=6)                                                                                                                                  
DecryptRTP/GCM-10                  160.0 ± 0%     144.0 ± 0%  -10.00% (p=0.002 n=6)                                                                                                                                  
geomean                            229.2          200.1       -12.71%                                                                                                                                                
                                                                                                                                                                                                                     
                              │ bench_old.txt │           bench_new.txt           │                                                                                                                                  
                              │   allocs/op   │ allocs/op   vs base               │                                                                                                                                  
EncryptRTP/CTR-100-10              4.000 ± 0%   2.000 ± 0%  -50.00% (p=0.002 n=6)                                                                                                                                    
EncryptRTP/CTR-1000-10             4.000 ± 0%   2.000 ± 0%  -50.00% (p=0.002 n=6)                                                                                                                                    
EncryptRTP/GCM-100-10              3.000 ± 0%   2.000 ± 0%  -33.33% (p=0.002 n=6)                                                                                                                                    
EncryptRTP/GCM-1000-10             3.000 ± 0%   2.000 ± 0%  -33.33% (p=0.002 n=6)                                                                                                                                    
EncryptRTPInPlace/CTR-100-10       3.000 ± 0%   1.000 ± 0%  -66.67% (p=0.002 n=6)                                                                                                                                    
EncryptRTPInPlace/CTR-1000-10      3.000 ± 0%   1.000 ± 0%  -66.67% (p=0.002 n=6)                                                                                                                                    
EncryptRTPInPlace/GCM-100-10       2.000 ± 0%   1.000 ± 0%  -50.00% (p=0.002 n=6)                                                                                                                                    
EncryptRTPInPlace/GCM-1000-10      2.000 ± 0%   1.000 ± 0%  -50.00% (p=0.002 n=6)                                                                                                                                    
DecryptRTP/CTR-10                  4.000 ± 0%   2.000 ± 0%  -50.00% (p=0.002 n=6)                                                                                                                                    
DecryptRTP/GCM-10                  3.000 ± 0%   2.000 ± 0%  -33.33% (p=0.002 n=6)                                                                                                                                    
geomean                            3.016        1.516       -49.74%

Sean-Der · 2025-12-19T18:02:27Z

Beautiful, nice work @thesyncim :)

codecov · 2025-12-19T18:04:00Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.63%. Comparing base (3ad2ef9) to head (a13e65a).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #355      +/-   ##
==========================================
- Coverage   82.64%   82.63%   -0.02%     
==========================================
  Files          19       19              
  Lines        1458     1457       -1     
==========================================
- Hits         1205     1204       -1     
  Misses        140      140              
  Partials      113      113

Flag	Coverage Δ
go	`82.63% <100.00%> (-0.02%)`	⬇️

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thesyncim · 2025-12-19T18:22:43Z

cc @atoppi

JoTurk

Change is amazing thank you.

srtp_cipher_aead_aes_gcm.go

asayyah · 2026-01-02T07:54:21Z

srtp_cipher_aead_aes_gcm.go

 	useCryptex bool
+
+	// Pre-allocated buffer for IV to avoid heap allocation in hot path
+	rtpIV [12]byte


assuming this is safe, wouldn't it better to just change rtpInitializationVector and rtpInitializationVector to directly use this buffer instead of allocating their own?

BTW I'm not familiar with this code base, so totally ignore me if it doesn't make sense.

@thesyncim Sorry i missed track of this PR.
what do you think about this refactor?

Oh that's a great idea @asayyah!

It's a super simple change @thesyncim I think will make the code easier to follow. Change that function to generateRTPInitializationVector and then we can merge.

Sorry I haven't been quicker on this :( it's a great change to get rid of these allocations.

If you don't have the time I can do it

I can pick this up later today

I did that. Could you check if everything looks good?

atoppi · 2026-01-09T12:06:23Z

I also did the same optimization for the RTCP path.

JoTurk

looks good to me, thank you and sorry again that we lost track of this.

JoTurk · 2026-01-09T12:21:17Z

@atoppi Do you mind if you update this branch, a rebase or a merge commit will do it. I don't want to push to your branch in case you have local changes.

atoppi · 2026-01-09T12:40:23Z

@atoppi Do you mind if you update this branch, a rebase or a merge commit will do it. I don't want to push to your branch in case you have local changes.

Done

JoTurk · 2026-01-09T12:47:01Z

@thesyncim @atoppi thank you so much for this.

thesyncim force-pushed the encrypt-decrypt-allocs branch from d611908 to b22aa75 Compare December 19, 2025 17:58

Reduce allocations in encrypt/decrypt RTP hot path

8f658b6

thesyncim force-pushed the encrypt-decrypt-allocs branch from b22aa75 to 8f658b6 Compare December 19, 2025 18:07

JoTurk reviewed Dec 19, 2025

View reviewed changes

srtp_cipher_aead_aes_gcm.go Outdated Show resolved Hide resolved

thesyncim force-pushed the encrypt-decrypt-allocs branch from fb02431 to ae33de0 Compare December 19, 2025 21:20

Reduce diff

57d6a38

thesyncim force-pushed the encrypt-decrypt-allocs branch from ae33de0 to 57d6a38 Compare December 19, 2025 21:29

Merge branch 'master' into encrypt-decrypt-allocs

2ab5660

thesyncim requested a review from JoTurk December 20, 2025 22:25

thesyncim added 2 commits December 21, 2025 10:40

Merge branch 'master' into encrypt-decrypt-allocs

45031f7

Merge branch 'master' into encrypt-decrypt-allocs

7b0bd25

asayyah reviewed Jan 2, 2026

View reviewed changes

atoppi added 3 commits January 9, 2026 13:10

Reuse pre-alloc IV before encrypt/decrypt

ab101f0

Use an IV buffer also for RTCP

233d953

Reset IV buffers when needed

66f2a85

atoppi force-pushed the encrypt-decrypt-allocs branch from aa390fb to 66f2a85 Compare January 9, 2026 12:11

JoTurk approved these changes Jan 9, 2026

View reviewed changes

Merge branch 'master' into encrypt-decrypt-allocs

a13e65a

JoTurk merged commit 030374f into pion:master Jan 9, 2026
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Reduce allocations in encrypt/decrypt RTP #355

Reduce allocations in encrypt/decrypt RTP #355

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