feat: Add NUT-XX Payment Request Bech32m Encoding specification#294
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callebtc merged 23 commits intocashubtc:mainfrom Jan 11, 2026
Merged
feat: Add NUT-XX Payment Request Bech32m Encoding specification#294callebtc merged 23 commits intocashubtc:mainfrom
callebtc merged 23 commits intocashubtc:mainfrom
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a1denvalu3
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cdk updated to use it here cashubtc/cdk@5388c28 |
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Add comprehensive specification for encoding Cashu payment requests using Bech32m format with TLV (Tag-Length-Value) serialization as an alternative to the existing CBOR+base64 format defined in NUT-18. - New specification file: 26.md defining NUT-26 - Updated README.md to include NUT-26 in the specification table The new Bech32m encoding format addresses several limitations of the legacy creqA (CBOR+base64) format: 1. **QR Code Efficiency**: Bech32m uppercase encoding is alphanumeric-mode compatible, resulting in 30-60% smaller QR codes 2. **Better Error Detection**: Built-in Bech32m checksums provide data integrity validation 3. **Improved Human Readability**: Clear `creqb1` prefix identifies the format 4. **Standards Alignment**: Consistent with Bitcoin addresses (BIP-173/350) and Lightning invoices - TLV-based serialization for flexible extensibility - Support for all NUT-18 payment request fields (id, amount, unit, mints, description, transports, NUT-10 conditions) - Compact encoding for common values (e.g., 'sat' as 0x00) - Nested TLV structures for complex types (transports, spending conditions) - Forward compatibility through unknown tag handling - Backward compatibility with legacy creqA format detection - Case-insensitive decoding with uppercase recommended for QR codes The specification is marked as optional and depends on NUT-18.
Co-authored-by: lollerfirst <43107113+lollerfirst@users.noreply.github.com>
Co-authored-by: lollerfirst <43107113+lollerfirst@users.noreply.github.com>
Co-authored-by: lollerfirst <43107113+lollerfirst@users.noreply.github.com>
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Fully implemented in cashubtc/cashu-ts#436 |
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We are missing a signal for P2BK as @robwoodgate mentioned here: cashubtc/cashu-ts#436 (review) |
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Wondering if some kind of general "tag" is possible that allows extension of the TLV schema without having to redefine it each time? I think this is what TSK was talking about on the p2bk nut pr? |
Egge21M
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We can "extend" to cater for extras like P2BK later. This is a solid base.
ACK @ a96323a
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This has been finalized and implemented for three weeks. No NACKs remain. I think this should be merged, but my green dont count. @callebtc |
callebtc
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Jan 11, 2026
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Add comprehensive specification for encoding Cashu payment requests using Bech32m format with TLV (Tag-Length-Value) serialization as an alternative to the existing CBOR+base64 format defined in NUT-18.
The new Bech32m encoding format addresses several limitations of the legacy creqA (CBOR+base64) format:
creqb1prefix identifies the formatThe specification is marked as optional and depends on NUT-18.