diff --git a/manifest b/manifest
index abc82a7f17..f8f98704b7 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sassert()\sstatements\sto\sverify\sthat\sthe\sSQLITE_OPEN_EXCLUSIVE\sflag\sis\salways\spassed\sto\sthe\sVFS\swhen\sopening\sa\stemporary\sfile.
-D 2022-08-16T10:52:35.403
+C Change\sthe\slegacy\sRC4-based\sPRNG\sto\suse\sthe\sRFC-7539\schacha20\salgorithm.
+D 2022-08-16T17:18:00.622
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -585,7 +585,7 @@ F src/pragma.c 6637d624c37a8909d3edfa9d7cf694d79b49d2a0827d8c52ef15dceb641783fa
 F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
 F src/prepare.c c62820c15dcb63013519c8e41d9f928d7478672cc902cfd0581c733c271dbf45
 F src/printf.c e99ee9741e79ae3873458146f59644276657340385ade4e76a5f5d1c25793764
-F src/random.c 097dc8b31b8fba5a9aca1697aeb9fd82078ec91be734c16bffda620ced7ab83c
+F src/random.c 546d6feb15ec69c1aafe9bb351a277cbb498fd5410e646add673acb805714960
 F src/resolve.c efea4e5fbecfd6d0a9071b0be0d952620991673391b6ffaaf4c277b0bb674633
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c 4750fbe9d8ecb7236baf7a9bea4299bb87126e08c209645666a0ae8f0efbe0fc
@@ -854,7 +854,7 @@ F test/corruptJ.test 4d5ccc4bf959464229a836d60142831ef76a5aa4
 F test/corruptK.test 5b4212fe346699831c5ad559a62c54e11c0611bdde1ea8423a091f9c01aa32af
 F test/corruptL.test ecce40d7b9b909a670a42a45d86e30d927735d7e7f09041af438b19529d35532
 F test/corruptM.test 7d574320e08c1b36caa3e47262061f186367d593a7e305d35f15289cc2c3e067
-F test/corruptN.test 60b5a62944b4f0029ba07edaa5fd8e670539d6b0a8d99db26c068d435675cbfe
+F test/corruptN.test 7c099d153a554001b4fb829c799b01f2ea6276cbc32479131e0db0da4efd9cc4
 F test/cost.test b11cdbf9f11ffe8ef99c9881bf390e61fe92baf2182bad1dbe6de59a7295c576
 F test/count.test cd4bd531066e8d77ef8fe1e3fc8253d042072e117ccab214b290cf83f1602249
 F test/countofview.test e17d6e6688cf74f22783c9ec6e788c0790ee4fbbaee713affd00b1ac0bb39b86
@@ -1999,8 +1999,9 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c271096736889530f392ff37e631a77f3bc9c46b290dbda245fa05249f4410fc
-R 3f7d8ed697988ef9ad8d4dda04b632a0
-U dan
-Z 207999dde59e8e595694810745e7b969
+P e123da49ccae61d591abded52f4721aa10f20d75935c9a3e3fe826a9b8df2317 a0d224c6a69941dad1f2b35edcc7ddee343b99eae2aeed74043461f3e97ef5b4
+R d14b7d3bd2befa6e359a3420d9b0b1d1
+T +closed a0d224c6a69941dad1f2b35edcc7ddee343b99eae2aeed74043461f3e97ef5b4
+U drh
+Z c066b8669f45d6d3a5c825d691d523b1
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 75e42a2853..f073344af1 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-e123da49ccae61d591abded52f4721aa10f20d75935c9a3e3fe826a9b8df2317
\ No newline at end of file
+a0f801151925e882e120f6ab685dcacb9d3268d25b52bc665c5b927bcc7dda1e
\ No newline at end of file
diff --git a/src/random.c b/src/random.c
index 87f9e2cecb..9335fc49da 100644
--- a/src/random.c
+++ b/src/random.c
@@ -22,16 +22,41 @@
 ** This structure is the current state of the generator.
 */
 static SQLITE_WSD struct sqlite3PrngType {
-  unsigned char isInit;          /* True if initialized */
-  unsigned char i, j;            /* State variables */
-  unsigned char s[256];          /* State variables */
+  u32 s[16];                 /* 64 bytes of chacha20 state */
+  u8 out[64];                /* Output bytes */
+  u8 n;                      /* Output bytes remaining */
 } sqlite3Prng;
 
+
+/* The RFC-7539 ChaCha20 block function
+*/
+#define ROTL(a,b) (((a) << (b)) | ((a) >> (32 - (b))))
+#define QR(a, b, c, d) (	\
+    a += b, d ^= a, d = ROTL(d,16),	\
+    c += d, b ^= c, b = ROTL(b,12),	\
+    a += b, d ^= a, d = ROTL(d, 8),	\
+    c += d, b ^= c, b = ROTL(b, 7))
+static void chacha_block(u32 *out, const u32 *in){
+  int i;
+  u32 x[16];
+  memcpy(x, in, 64);
+  for(i=0; i<10; i++){
+    QR(x[0], x[4], x[ 8], x[12]);
+    QR(x[1], x[5], x[ 9], x[13]);
+    QR(x[2], x[6], x[10], x[14]);
+    QR(x[3], x[7], x[11], x[15]);
+    QR(x[0], x[5], x[10], x[15]);
+    QR(x[1], x[6], x[11], x[12]);
+    QR(x[2], x[7], x[ 8], x[13]);
+    QR(x[3], x[4], x[ 9], x[14]);
+  }
+  for(i=0; i<16; i++) out[i] = x[i]+in[i];
+}
+
 /*
 ** Return N random bytes.
 */
 void sqlite3_randomness(int N, void *pBuf){
-  unsigned char t;
   unsigned char *zBuf = pBuf;
 
   /* The "wsdPrng" macro will resolve to the pseudo-random number generator
@@ -61,53 +86,46 @@ void sqlite3_randomness(int N, void *pBuf){
 
   sqlite3_mutex_enter(mutex);
   if( N<=0 || pBuf==0 ){
-    wsdPrng.isInit = 0;
+    wsdPrng.s[0] = 0;
     sqlite3_mutex_leave(mutex);
     return;
   }
 
   /* Initialize the state of the random number generator once,
-  ** the first time this routine is called.  The seed value does
-  ** not need to contain a lot of randomness since we are not
-  ** trying to do secure encryption or anything like that...
-  **
-  ** Nothing in this file or anywhere else in SQLite does any kind of
-  ** encryption.  The RC4 algorithm is being used as a PRNG (pseudo-random
-  ** number generator) not as an encryption device.
+  ** the first time this routine is called.
   */
-  if( !wsdPrng.isInit ){
+  if( wsdPrng.s[0]==0 ){
     sqlite3_vfs *pVfs = sqlite3_vfs_find(0);
-    int i;
-    char k[256];
-    wsdPrng.j = 0;
-    wsdPrng.i = 0;
+    static const u32 chacha20_init[] = {
+      0x61707865, 0x3320646e, 0x79622d32, 0x6b206574
+    };
+    memcpy(&wsdPrng.s[0], chacha20_init, 16);
     if( NEVER(pVfs==0) ){
-      memset(k, 0, sizeof(k));
+      memset(&wsdPrng.s[4], 0, 44);
     }else{
-      sqlite3OsRandomness(pVfs, 256, k);
+      sqlite3OsRandomness(pVfs, 44, (char*)&wsdPrng.s[4]);
     }
-    for(i=0; i<256; i++){
-      wsdPrng.s[i] = (u8)i;
-    }
-    for(i=0; i<256; i++){
-      wsdPrng.j += wsdPrng.s[i] + k[i];
-      t = wsdPrng.s[wsdPrng.j];
-      wsdPrng.s[wsdPrng.j] = wsdPrng.s[i];
-      wsdPrng.s[i] = t;
-    }
-    wsdPrng.isInit = 1;
+    wsdPrng.s[15] = wsdPrng.s[12];
+    wsdPrng.s[12] = 0;
+    wsdPrng.n = 0;
   }
 
   assert( N>0 );
-  do{
-    wsdPrng.i++;
-    t = wsdPrng.s[wsdPrng.i];
-    wsdPrng.j += t;
-    wsdPrng.s[wsdPrng.i] = wsdPrng.s[wsdPrng.j];
-    wsdPrng.s[wsdPrng.j] = t;
-    t += wsdPrng.s[wsdPrng.i];
-    *(zBuf++) = wsdPrng.s[t];
-  }while( --N );
+  while( 1 /* exit by break */ ){
+    if( N<=wsdPrng.n ){
+      memcpy(zBuf, &wsdPrng.out[wsdPrng.n-N], N);
+      wsdPrng.n -= N;
+      break;
+    }
+    if( wsdPrng.n>0 ){
+      memcpy(zBuf, wsdPrng.out, wsdPrng.n);
+      N -= wsdPrng.n;
+      zBuf += wsdPrng.n;
+    }
+    wsdPrng.s[12]++;
+    chacha_block((u32*)wsdPrng.out, wsdPrng.s);
+    wsdPrng.n = 64;
+  }
   sqlite3_mutex_leave(mutex);
 }
 
diff --git a/test/corruptN.test b/test/corruptN.test
index 4685788223..376325f5c5 100644
--- a/test/corruptN.test
+++ b/test/corruptN.test
@@ -141,12 +141,15 @@ do_test 2.0 {
 | end c-b92b.txt.db
 }]} {}
 
-prng_seed 0 db
-do_catchsql_test 2.1 {
-SELECT count(*) FROM sqlite_schema;
-WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<1000)
-INSERT INTO t1(a) SELECT randomblob(null) FROM c;
-} {1 {database disk image is malformed}}
+# This test only works with the legacy RC4 PRNG
+if 0 {
+  prng_seed 0 db
+  do_catchsql_test 2.1 {
+  SELECT count(*) FROM sqlite_schema;
+  WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<1000)
+  INSERT INTO t1(a) SELECT randomblob(null) FROM c;
+  } {1 {database disk image is malformed}}
+}
 
 reset_db
 if {![info exists ::G(perm:presql)]} {