/dev/random broken?

/dev/random broken?

[Luca T.]

Hello,
i am not sure if this is a kernel/module problem but so it seems to me.
My computer is an AMD 2000+ with an ABIT motherboard, my kernel version 
is 2.4.21-0.13mdk (but i tried it with 2.4.21-0.18mdk too and it doesn't 
work either).

If i give this command:
  dd if=/dev/zero of=./xxx bs=1024 count=100
it will work perfectly. But if i try to do the same reading from 
/dev/random with this command:
  dd if=/dev/random of=./xxx bs=1024 count=100
it will just sit there and stare at me until i move the mouse... and 
then the program will exit without any error message (i checked in 
/var/log/messages too and there is no message there either about this).

Is this a bug? If yes... do you have any idea that would help me fix it?

Thank you,
     Luca

/dev/random broken?

[Luca T.]

Hello,
i am not sure if this is a kernel/module problem but so it seems to me.
My computer is an AMD 2000+ with an ABIT motherboard, my kernel version
is 2.4.21-0.13mdk (but i tried it with 2.4.21-0.18mdk too and it doesn't
work either).

If i give this command:
  dd if=/dev/zero of=./xxx bs=1024 count=100
it will work perfectly. But if i try to do the same reading from
/dev/random with this command:
  dd if=/dev/random of=./xxx bs=1024 count=100
it will just sit there and stare at me until i move the mouse... and
then the program will exit without any error message (i checked in
/var/log/messages too and there is no message there either about this).

Is this a bug? If yes... do you have any idea that would help me fix it?

Thank you,
     Luca

P.S.: I add here more info about my configuration:

[luca@ATH2000 luca]$ cat /proc/version
Linux version 2.4.21-0.13mdk (flepied@bi.mandrakesoft.com) (gcc version 
3.2.2 (Mandrake Linux 9.1 3.2.2-3mdk)) #1 Fri Mar 14 15:08:06 EST 2003

[luca@ATH2000 luca]$ cat /proc/modules
saa7113h                7776   0 (autoclean)
rivatv                 68156   0
i2c-algo-bit            9064   2 [rivatv]
i2c-core               21192   0 [saa7113h rivatv i2c-algo-bit]
appletalk              25700   1 (autoclean)
ipx                    21252   1 (autoclean)
parport_pc             25096   1 (autoclean)
lp                      8096   0 (autoclean)
parport                34176   1 (autoclean) [parport_pc lp]
agpgart                40896   3 (autoclean) [rivatv]
NVdriver             1149824  10 (autoclean)
nls_cp437               5148   2 (autoclean)
nls_iso8859-1           3516   2 (autoclean)
smbfs                  40144   2 (autoclean)
es1371                 29000   1
soundcore               6276   0 [es1371]
ac97_codec             12488   0 [es1371]
gameport                3316   0 [es1371]
nfsd                   74256   0 (autoclean)
af_packet              14952   0 (autoclean)
sr_mod                 16920   0 (autoclean)
floppy                 55132   0
8139too                17160   1 (autoclean)
mii                     3832   0 (autoclean) [8139too]
supermount             15296   3 (autoclean)
ide-cd                 33856   0
cdrom                  31648   0 [sr_mod ide-cd]
ide-scsi               11280   0
pwc                    45064   0
videodev                7872   3 [rivatv pwc]
usbmouse                2936   0 (unused)
keybdev                 2720   0 (unused)
mousedev                5268   0 (unused)
hid                    20900   0 (unused)
evdev                   5632   1
wacom                   7096   0 (unused)
input                   5664   0 [usbmouse keybdev mousedev hid evdev wacom]
printer                 8448   0 (unused)
usb-uhci               24652   0 (unused)
usbcore                72992   1 [pwc usbmouse hid wacom printer usb-uhci]
rtc                     8060   0 (autoclean)
reiserfs              175120   2
sd_mod                 11548   0 (unused)
ataraid                 6852   0 (unused)
scsi_mod               91796   3 [sr_mod ide-scsi sd_mod]

[luca@ATH2000 luca]$ cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 6
model           : 8
model name      : AMD Athlon(tm) XP 2000+
stepping        : 0
cpu MHz         : 1667.412
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow
bogomips        : 3329.22


[luca@ATH2000 luca]$ cat /proc/ioports
0000-001f : dma1
0020-003f : pic1
0040-005f : timer
0060-006f : keyboard
0070-007f : rtc
0080-008f : dma page reg
00a0-00bf : pic2
00c0-00df : dma2
00f0-00ff : fpu
01f0-01f7 : ide0
02f8-02ff : serial(auto)
0378-037a : parport0
037b-037f : parport0
03c0-03df : vga+
03f6-03f6 : ide0
03f8-03ff : serial(auto)
0cf8-0cff : PCI conf1
c000-c0ff : Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+
   c000-c0ff : 8139too
c400-c43f : Ensoniq 5880 AudioPCI
   c400-c43f : es1371
c800-c80f : VIA Technologies, Inc. VT82C586B PIPC Bus Master IDE
   c800-c807 : ide0
   c808-c80f : ide1
cc00-cc1f : VIA Technologies, Inc. USB
   cc00-cc1f : usb-uhci
d000-d01f : VIA Technologies, Inc. USB (#2)
   d000-d01f : usb-uhci
d400-d407 : Triones Technologies, Inc. HPT366/368/370/370A/372
d800-d803 : Triones Technologies, Inc. HPT366/368/370/370A/372
dc00-dc07 : Triones Technologies, Inc. HPT366/368/370/370A/372
   dc00-dc07 : ide3
e000-e003 : Triones Technologies, Inc. HPT366/368/370/370A/372
   e002-e002 : ide3
e400-e4ff : Triones Technologies, Inc. HPT366/368/370/370A/372
   e400-e407 : ide2
   e408-e40f : ide3
   e410-e4ff : HPT372

[luca@ATH2000 luca]$ cat /proc/ioports
0000-001f : dma1
0020-003f : pic1
0040-005f : timer
0060-006f : keyboard
0070-007f : rtc
0080-008f : dma page reg
00a0-00bf : pic2
00c0-00df : dma2
00f0-00ff : fpu
01f0-01f7 : ide0
02f8-02ff : serial(auto)
0378-037a : parport0
037b-037f : parport0
03c0-03df : vga+
03f6-03f6 : ide0
03f8-03ff : serial(auto)
0cf8-0cff : PCI conf1
c000-c0ff : Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+
   c000-c0ff : 8139too
c400-c43f : Ensoniq 5880 AudioPCI
   c400-c43f : es1371
c800-c80f : VIA Technologies, Inc. VT82C586B PIPC Bus Master IDE
   c800-c807 : ide0
   c808-c80f : ide1
cc00-cc1f : VIA Technologies, Inc. USB
   cc00-cc1f : usb-uhci
d000-d01f : VIA Technologies, Inc. USB (#2)
   d000-d01f : usb-uhci
d400-d407 : Triones Technologies, Inc. HPT366/368/370/370A/372
d800-d803 : Triones Technologies, Inc. HPT366/368/370/370A/372
dc00-dc07 : Triones Technologies, Inc. HPT366/368/370/370A/372
   dc00-dc07 : ide3
e000-e003 : Triones Technologies, Inc. HPT366/368/370/370A/372
   e002-e002 : ide3
e400-e4ff : Triones Technologies, Inc. HPT366/368/370/370A/372
   e400-e407 : ide2
   e408-e40f : ide3
   e410-e4ff : HPT372
[luca@ATH2000 luca]$
[luca@ATH2000 luca]$ cat /proc/iomem
00000000-0009fbff : System RAM
0009fc00-0009ffff : reserved
000a0000-000bffff : Video RAM area
000c0000-000c7fff : Video ROM
000cc000-000cfdff : Extension ROM
000f0000-000fffff : System ROM
00100000-1ffeffff : System RAM
   00100000-00260a36 : Kernel code
   00260a37-0037831f : Kernel data
1fff0000-1fff2fff : ACPI Non-volatile Storage
1fff3000-1fffffff : ACPI Tables
d0000000-d7ffffff : VIA Technologies, Inc. VT8367 [KT266]
d8000000-d9ffffff : PCI Bus #01
   d8000000-d9ffffff : nVidia Corporation NV5 [Riva TnT2]
     d8000000-d9ffffff : rivatv
da000000-dbffffff : PCI Bus #01
   da000000-daffffff : nVidia Corporation NV5 [Riva TnT2]
     da000000-daffffff : rivatv
dd000000-dd0000ff : Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+
   dd000000-dd0000ff : 8139too
fec00000-fec00fff : reserved
fee00000-fee00fff : reserved
ffff0000-ffffffff : reserved


[root@ATH2000 luca]# lspci -vvv
00:00.0 Host bridge: VIA Technologies, Inc. VT8366/A/7 [Apollo KT266/A/333]
         Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz+ UDF- FastB2B- ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort+ >SERR- <PERR-
         Latency: 0
         Region 0: Memory at d0000000 (32-bit, prefetchable) [size=128M]
         Capabilities: [a0] AGP version 2.0
                 Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- 
HTrans- 64bit- FW- AGP3- Rate=x1,x2
                 Command: RQ=1 ArqSz=0 Cal=0 SBA- AGP+ GART64- 64bit- 
FW- Rate=x2
         Capabilities: [c0] Power Management version 2
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:01.0 PCI bridge: VIA Technologies, Inc. VT8366/A/7 [Apollo 
KT266/A/333 AGP] (prog-if 00 [Normal decode])
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR+ FastB2B-
         Status: Cap+ 66Mhz+ UDF- FastB2B- ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort+ >SERR- <PERR-
         Latency: 0
         Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
         I/O behind bridge: 0000f000-00000fff
         Memory behind bridge: da000000-dbffffff
         Prefetchable memory behind bridge: d8000000-d9ffffff
         BridgeCtl: Parity- SERR- NoISA+ VGA+ MAbort- >Reset- FastB2B-
         Capabilities: [80] Power Management version 2
                 Flags: PMEClk- DSI- D1+ D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:0d.0 Ethernet controller: Realtek Semiconductor Co., Ltd. 
RTL-8139/8139C/8139C+ (rev 10)
         Subsystem: Unex Technology Corp. ND010
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz- UDF- FastB2B+ ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort- >SERR- <PERR-
         Latency: 32 (8000ns min, 16000ns max)
         Interrupt: pin A routed to IRQ 5
         Region 0: I/O ports at c000 [size=256]
         Region 1: Memory at dd000000 (32-bit, non-prefetchable) [size=256]
         Capabilities: [50] Power Management version 2
                 Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA 
PME(D0-,D1+,D2+,D3hot+,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:0f.0 Multimedia audio controller: Ensoniq 5880 AudioPCI (rev 02)
         Subsystem: Ensoniq Creative Sound Blaster AudioPCI128
         Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=slow >TAbort- 
<TAbort- <MAbort+ >SERR- <PERR-
         Latency: 32 (3000ns min, 32000ns max)
         Interrupt: pin A routed to IRQ 5
         Region 0: I/O ports at c400 [size=64]
         Capabilities: [dc] Power Management version 1
                 Flags: PMEClk- DSI+ D1- D2+ AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:11.0 ISA bridge: VIA Technologies, Inc. VT8233A ISA Bridge
         Subsystem: VIA Technologies, Inc. VT8233A ISA Bridge
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping+ SERR- FastB2B-
         Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort- >SERR- <PERR-
         Latency: 0
         Capabilities: [c0] Power Management version 2
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:11.1 IDE interface: VIA Technologies, Inc. VT82C586/B/686A/B PIPC Bus 
Master IDE (rev 06) (prog-if 8a [Master SecP PriP])
         Subsystem: VIA Technologies, Inc. VT8235 Bus Master 
ATA133/100/66/33 IDE
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz- UDF- FastB2B+ ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort- >SERR- <PERR-
         Latency: 32
         Interrupt: pin A routed to IRQ 0
         Region 4: I/O ports at c800 [size=16]
         Capabilities: [c0] Power Management version 2
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:11.2 USB Controller: VIA Technologies, Inc. USB (rev 23) (prog-if 00 
[UHCI])
         Subsystem: VIA Technologies, Inc. (Wrong ID) USB Controller
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort- >SERR- <PERR-
         Latency: 32, cache line size 08
         Interrupt: pin D routed to IRQ 11
         Region 4: I/O ports at cc00 [size=32]
         Capabilities: [80] Power Management version 2
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:11.3 USB Controller: VIA Technologies, Inc. USB (rev 23) (prog-if 00 
[UHCI])
         Subsystem: VIA Technologies, Inc. (Wrong ID) USB Controller
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort- >SERR- <PERR-
         Latency: 32, cache line size 08
         Interrupt: pin D routed to IRQ 11
         Region 4: I/O ports at d000 [size=32]
         Capabilities: [80] Power Management version 2
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:13.0 RAID bus controller: Triones Technologies, Inc. 
HPT366/368/370/370A/372 (rev 05)
         Subsystem: Triones Technologies, Inc. HPT370A
         Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz+ UDF- FastB2B- ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort- >SERR- <PERR-
         Latency: 120 (2000ns min, 2000ns max), cache line size 08
         Interrupt: pin A routed to IRQ 10
         Region 0: I/O ports at d400 [size=8]
         Region 1: I/O ports at d800 [size=4]
         Region 2: I/O ports at dc00 [size=8]
         Region 3: I/O ports at e000 [size=4]
         Region 4: I/O ports at e400 [size=256]
         Expansion ROM at <unassigned> [disabled] [size=128K]
         Capabilities: [60] Power Management version 2
                 Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-

01:00.0 VGA compatible controller: nVidia Corporation NV5 [RIVA 
TNT2/TNT2 Pro] (rev 11) (prog-if 00 [VGA])
         Subsystem: Asustek Computer, Inc. AGP-V3800 SGRAM
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B-
         Status: Cap+ 66Mhz+ UDF- FastB2B+ ParErr- DEVSEL=medium 
 >TAbort- <TAbort- <MAbort- >SERR- <PERR-
         Latency: 248 (1250ns min, 250ns max)
         Interrupt: pin A routed to IRQ 11
         Region 0: Memory at da000000 (32-bit, non-prefetchable) [size=16M]
         Region 1: Memory at d8000000 (32-bit, prefetchable) [size=32M]
         Expansion ROM at <unassigned> [disabled] [size=64K]
         Capabilities: [60] Power Management version 1
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 PME-Enable- DSel=0 DScale=0 PME-
         Capabilities: [44] AGP version 2.0
                 Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- 
HTrans- 64bit- FW- AGP3- Rate=x1,x2
                 Command: RQ=32 ArqSz=0 Cal=0 SBA- AGP+ GART64- 64bit- 
FW- Rate=x2

Re: /dev/random broken?

[Rudo Thomas]

> Is this a bug?

No, it is not. If there's not enough random data available, reading from
/dev/random will block. Moving the mouse around will generate some interrupts
(or other stuff) that contribute to the entropy...

Rudo.

Re: /dev/random broken?

[Måns Rullgård]

"Luca T." <luca-t@libero.it> writes:

> i am not sure if this is a kernel/module problem but so it seems to me.
> My computer is an AMD 2000+ with an ABIT motherboard, my kernel
> version is 2.4.21-0.13mdk (but i tried it with 2.4.21-0.18mdk too and
> it doesn't work either).
>
> If i give this command:
>   dd if=/dev/zero of=./xxx bs=1024 count=100
> it will work perfectly. But if i try to do the same reading from
> /dev/random with this command:
>   dd if=/dev/random of=./xxx bs=1024 count=100
> it will just sit there and stare at me until i move the mouse... and
> then the program will exit without any error message (i checked in
> /var/log/messages too and there is no message there either about this).
>
> Is this a bug? If yes... do you have any idea that would help me fix it?

It's not a bug.  The system needs to collect some randomness before
you can get any data.  The mouse is considered random, as are various
other devices.  If you need lots of random data, and are satisfied
with pseudo-random numbers, you can use /dev/urandom instead.

-- 
Måns Rullgård
mru@users.sf.net

Re: /dev/random broken?

[Tom Vier]

On Sun, Jun 29, 2003 at 01:18:09AM +0200, Luca T. wrote:
>  dd if=/dev/random of=./xxx bs=1024 count=100
> it will just sit there and stare at me until i move the mouse... and 
> Is this a bug? If yes... do you have any idea that would help me fix it?

no, use /dev/urandom. man urandom. read drivers/char/random.c.

-- 
Tom Vier <tmv@comcast.net>
DSA Key ID 0xE6CB97DA

Re: /dev/random broken?

[Justin Pryzby]

/dev/urandom is what you want; it makes up its own entropy.  /dev/random
uses entropy from user input (low order bits I imagine).  I assume that
this is how other unixes work, too.

Justin

On Sun, Jun 29, 2003 at 02:16:02AM +0000, Luca T. wrote:
> 
> Hello,
> i am not sure if this is a kernel/module problem but so it seems to me.
> My computer is an AMD 2000+ with an ABIT motherboard, my kernel version
> is 2.4.21-0.13mdk (but i tried it with 2.4.21-0.18mdk too and it doesn't
> work either).
> 
> If i give this command:
>  dd if=/dev/zero of=./xxx bs=1024 count=100
> it will work perfectly. But if i try to do the same reading from
> /dev/random with this command:
>  dd if=/dev/random of=./xxx bs=1024 count=100
> it will just sit there and stare at me until i move the mouse... and
> then the program will exit without any error message (i checked in
> /var/log/messages too and there is no message there either about this).
> 
> Is this a bug? If yes... do you have any idea that would help me fix it?
> 
> Thank you,
>     Luca
> 
> -
> To unsubscribe from this list: send the line 'unsubscribe linux-kernel' in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/

Re: /dev/random broken?

[Robert Love]

On Sat, 2003-06-28 at 19:10, Justin Pryzby wrote:

> /dev/urandom is what you want; it makes up its own entropy.  /dev/random
> uses entropy from user input (low order bits I imagine).  I assume that
> this is how other unixes work, too.

Actually, no. Both device files use entropy from the same location (the
entropy pool), which is derived from the same sources (various interrupt
timings and whatnot).

The difference between the two is that /dev/random keeps track of the
inherent entropy in the pool and will block when the entropy grows too
small. This is done as protection against any possible flaws in the
one-way hash employed on outgoing data. Theoretically, if someone was
able to break SHA-1, and they obtained a sufficiently large percentage
of the output data, they could theoretically determine some theoretical
state about the entropy pool. To prevent this theoretical attack,
/dev/random will not return any data while the entropy estimate is not
positive. This ensures there is enough entropy in the pool such that,
even if a single attacker has seen all the output thus far, they cannot
learn of the pool's state.

Also, as far as other Unix systems, I think /dev/random was first in
Linux. I know Mac OS X has /dev/random and /dev/urandom, but they both
behave like Linux's /dev/urandom.

	Robert Love

Re: /dev/random broken?

[Valdis.Kletnieks]

[-- Attachment #1: Type: text/plain, Size: 823 bytes --]

On Sat, 28 Jun 2003 19:10:18 PDT, Justin Pryzby said:
> /dev/urandom is what you want; it makes up its own entropy.  /dev/random
> uses entropy from user input (low order bits I imagine).

Strictly speaking, urandom doesn't "make up" any entropy - it generates
a pseudorandom stream of bits of arbitrary length using a small chunk of
entropy from the entropy pool.  That's why it's able to generate multi-megabyte
streams of bits even when the entropy pool is empty - it is generating a
fixed but unpredictable stream based on the initial entropy.

The distinction is important mostly to cryptographers - for almost all
practical uses, the pseudorandom stream of bits produced by urandom
is quite sufficient, much faster, and leaves the entropy pool untouched
for those applications that *do* care about the difference....

[-- Attachment #2: Type: application/pgp-signature, Size: 226 bytes --]

Re: /dev/random broken?

[H. Peter Anvin]

Followup to:  <3EFE23A5.2000608@libero.it>
By author:    "Luca T." <luca-t@libero.it>
In newsgroup: linux.dev.kernel
>
> Hello,
> i am not sure if this is a kernel/module problem but so it seems to me.
> My computer is an AMD 2000+ with an ABIT motherboard, my kernel version
> is 2.4.21-0.13mdk (but i tried it with 2.4.21-0.18mdk too and it doesn't
> work either).
> 

In addition to the other posts in this thread, you may want to load
the hwrng driver and run rngd.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
Architectures needed: ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64