fix(ciphers): chunk RSA plaintext by bytes not runes to prevent OAEP overflow on UTF-8 input#319
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…d-4b65-affb-3d6f61fb8f82 init idempotency: 99171cbe-7c27-4976-a999-931b834b5d62:d97cc852-279d-4b65-affb-3d6f61fb8f82:init
idempotency: pm:run Co-authored-by: Max Warner (pm) <forge-agent+pm@simple-forge.com>
idempotency: architect:run Co-authored-by: Dan Johnson (architect) <forge-agent+architect@simple-forge.com>
…P overflow on UTF-8 input EncryptLargeString was splitting the plaintext using lo.ChunkString, which operates on rune count. For a 2048-bit key the chunk size was 128 runes — safe for ASCII (128 bytes ≤ 190-byte OAEP-SHA256 limit) but wrong for multi-byte UTF-8: a 128-rune box-drawing string encodes to 384 bytes, blowing past the limit and producing "crypto/rsa: message too long for RSA key size". Replace the rune-based loop with a byte-slice loop using the correct OAEP-SHA256 maximum plaintext size: k − 2·hLen − 2 = 256 − 64 − 2 = 190 bytes for a 2048-bit key. Existing ciphertext is unaffected — DecryptLargeString is chunk-size agnostic. Also add a TODO comment on EncryptWithPublicRSAKey noting its SHA-512 / SHA-256 inconsistency with EncryptLargeString; no behavioural change there. Adds three regression tests covering box-drawing characters (U+2500, 3 B each), emoji (U+1F600, 4 B each), and a mid-rune byte-boundary split. Fixes: sc secrets add/hide failing with UTF-8 secret files.
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idempotency: developer:run Co-authored-by: David Black (developer) <forge-agent+developer@simple-forge.com>
Semgrep Scan ResultsRepository:
Scanned at 2026-06-12 17:23 UTC |
Security Scan ResultsRepository:
Scanned at 2026-06-12 17:24 UTC |
idempotency: qa:run Co-authored-by: Maria Currie (qa) <forge-agent+qa@simple-forge.com>
idempotency: devops:run Co-authored-by: William Smith (devops) <forge-agent+devops@simple-forge.com>
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Jun 12, 2026
universe-ops
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Jun 12, 2026
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Summary
EncryptLargeStringwas chunking plaintext withlo.ChunkString(rune-count), but RSA-OAEP enforces a byte limit. A 128-rune chunk of 3-byte UTF-8 characters = 384 bytes — well above the 190-byte OAEP-SHA256 limit for a 2048-bit key — causingcrypto/rsa: message too long for RSA key size.maxPlain = k − 2·hLen − 2 = 190 bytesfor 2048-bit / SHA-256.DecryptLargeStringis chunk-size agnostic.// TODO:comment onEncryptWithPublicRSAKeynoting its SHA-512/SHA-256 inconsistency withEncryptLargeString; no functional change to that function.Changed files
pkg/api/secrets/ciphers/encryption.golo.ChunkStringRSA branch with byte-slice loop; add TODO comment onEncryptWithPublicRSAKeypkg/api/secrets/ciphers/encryption_test.goTest plan
go test ./pkg/api/secrets/ciphers/... -count=1— all tests pass (green locally)TestRSAEncryptionDecryption/RSA_encrypt/decrypt_UTF-8_multi-byte_string_(box-drawing)— was failing before fix (360 B > 190 B limit)TestRSAEncryptionDecryption/RSA_encrypt/decrypt_emoji-dense_string— was failing before fix (400 B > 190 B limit)TestRSAEncryptionDecryption/RSA_chunk_boundaries_do_not_corrupt_multi-byte_sequences— verifies mid-rune byte splits round-trip correctlyRSA encrypt/decrypt large string(ASCII) still passesWorkflow run
https://app.simple-forge.com/agent-workflow-runs/d97cc852-279d-4b65-affb-3d6f61fb8f82
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