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Merged
merged 5 commits into from
Sep 25, 2025
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docs: make explicit that you can use ipfs cid format to convert both ways #2126

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510ca0d
Make explicit that you can use ipfs cid format to convert both ways
dannyob Aug 28, 2025
5a927e8
Merge branch 'main' into patch-1
gammazero Sep 25, 2025
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Merge branch 'main' into patch-1
gammazero Sep 25, 2025
cad2d86
docs: clarify dag-pb requirement for CIDv1 to CIDv0 conversion
lidel Sep 25, 2025
6e6567a
Merge branch 'main' into patch-1
lidel Sep 25, 2025
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13 changes: 12 additions & 1 deletion docs/concepts/content-addressing.md
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Original file line number Diff line number Diff line change
Expand Up @@ -145,7 +145,18 @@
//> 'bafybeihdwdcefgh4dqkjv67uzcmw7ojee6xedzdetojuzjevtenxquvyku'
```

### v1 to v0
### v1 to v0

Conversion from CIDv1 to CIDv0 is only possible when the CIDv1 uses the `dag-pb` codec (0x70), as CIDv0 only supports `dag-pb`. CIDs using other codecs like `raw` (0x55), `dag-cbor` (0x71), or `dag-json` (0x0129) cannot be converted to CIDv0.

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[vale] reported by reviewdog 🐶
[docs.PLNSpelling] Did you really mean 'codecs'?

Raw Output:
{"message": "[docs.PLNSpelling] Did you really mean 'codecs'?", "location": {"path": "docs/concepts/content-addressing.md", "range": {"start": {"line": 150, "column": 146}}}, "severity": "ERROR"}

The built-in `ipfs cid format` command can be used to convert `dag-pb` from CIDv1 to CIDv0 from the command line:

```
$ ipfs cid format -v 0 bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi
QmbWqxBEKC3P8tqsKc98xmWNzrzDtRLMiMPL8wBuTGsMnR
```

Note: The above example works because `bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi` uses the `dag-pb` codec. Attempting to convert a CIDv1 with a different codec will result in an error.

Given a CID v1, JS users can convert back to v0 using the `toV0()` method provided by the [`multiformats`](https://www.npmjs.com/package/multiformats) library:

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