rsa vs aes-gcm

Short answerBy steady daily use, rsa is bigger: 717,631 real downloads a day against 653,891 for aes-gcm (1.1x). 1,182 crates depend on rsa and 1,968 on aes-gcm. rsa last shipped 18 days ago, aes-gcm 2 months ago.

rsa

Widely used

Widely used and steady.

1,182 crates depend on it; downloads jump on release days (1.4x the baseline).

Pure Rust RSA implementation

aes-gcm

Widely used

Widely used and gaining.

1,968 crates depend on it; downloads don't spike on releases.

Pure Rust implementation of the AES-GCM (Galois/Counter Mode) Authenticated Encryption with Associated Data (AEAD) Cipher with optional architecture-specific hardware acceleration

rsaaes-gcm · 100% = that crate's normal quiet day, so a spike to 300% is triple its usual traffic

Every number, side by side

Same window, same method	rsa	aes-gcm
Real downloads a day	717,631	653,891
Crates that depend on it	1,182	1,968
Last release	0.10.0-rc.19, 18 days ago	0.11.1, 2 months ago
Trend vs the field	-4%	+20%
Release-window share	3.0%	1.8%
Downloads in the window	63,841,064	60,777,667
All-time downloads	252,034,231	187,606,424
Versions published	65	37
License	MIT OR Apache-2.0	Apache-2.0 OR MIT
MSRV	1.85	1.85
First published	Jul 24, 2018	Aug 16, 2019

Which to pick

Downloads tell you what is common, not what fits. Each crate's own description above says what it is for; when the jobs differ, pick by the job.
When both fit, prefer the one more crates depend on (aes-gcm, 1,968 dependents): more eyes, more answered questions, and you may already have it in your tree.
Check the release dates against your own pace: rsa 18 days ago, aes-gcm 2 months ago.

Also in this space

ringWidely usedAn experiment2,112,308 a day, 1,837 dependents pem-rfc7468Pulled inPEM Encoding (RFC 7468) for PKIX, PKCS, and CMS Structures, implementing a strict subset of the original...1,099,295 a day, 73 dependents aeadEstablishedTraits for Authenticated Encryption with Associated Data (AEAD) algorithms, such as AES-GCM as...824,924 a day, 210 dependents aws-lc-rsEstablishedaws-lc-rs is a cryptographic library using AWS-LC for its cryptographic operations. This library strives to...1,156,444 a day, 474 dependents

Compare 4 of them side by side →

Method

Real downloads = the median day with no release that day or the day before, from the crates.io API (Jul 27, 2026 to Oct 23, 2026). Raw crates.io counts include CI and bots and run high (why); the method is from our 90-day study.

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