dataHash

Returns the file's content hash as recorded in the active C2PA manifest. This hash is used as a public input to the zero-knowledge proof.

Usage

import { VerifiableFile } from '@succinctlabs/react-native-zcam1';
 
const verifiable = new VerifiableFile(photoPath);
const hash = verifiable.dataHash();
 
console.log('Content hash:', hash);

Returns

string | undefined - The manifest data hash (base64-encoded string), or undefined if not available.

Example

import { useState } from 'react';
import { Button, Text, View, StyleSheet } from 'react-native';
import { VerifiableFile } from '@succinctlabs/react-native-zcam1';
import { launchImageLibrary } from 'react-native-image-picker';
 
function HashDisplayScreen() {
  const [hash, setHash] = useState<string>('');
 
  const getHash = async () => {
    const response = await launchImageLibrary({ mediaType: 'photo' });
    const uri = response.assets?.[0]?.uri;
    
    if (!uri) return;
 
    try {
      const verifiable = new VerifiableFile(uri);
      const photoHash = verifiable.dataHash();
      
      if (photoHash) {
        setHash(`Hash: ${photoHash.substring(0, 32)}...`);
      } else {
        setHash('No hash available');
      }
    } catch (error: any) {
      setHash(`Error: ${error.message}`);
    }
  };
 
  return (
    <View style={styles.container}>
      <Button title="Get Photo Hash" onPress={getHash} />
      {hash && <Text style={styles.hash}>{hash}</Text>}
    </View>
  );
}

Notes

The hash is computed from the photo's actual file content
This hash is used as a public input when verifying the zero-knowledge proof
The hash is base64-encoded for readability and compatibility
Computed lazily on first access and cached for subsequent calls